Steering method, steering control apparatus, control system, computing device, and vehicle

Abstract

A steering method, a steering control apparatus, a control system, a computing device, and a vehicle, which are applied to the technical field of vehicle control. The steering method comprises: controlling a first front wheel of a vehicle to be stationary relative to the vehicle; and driving a first rear wheel and a second rear wheel of the vehicle to rotate, such that the vehicle steers by pivoting on the first front wheel, wherein the driving direction of the first rear wheel is opposite to the driving direction of the second rear wheel.

Description

Steering method, steering control device, control system, computing equipment and vehicle

[0001] This application claims priority to Chinese patent application No. 202410709227.7, filed on May 31, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of vehicle control technology, and in particular to a steering method, steering control device, control system, computing device, and vehicle. Background Technology

[0003] With the advancement of industrial technology and the improvement of people's living standards, automobiles, as a means of transportation, play an increasingly important role in people's daily lives, and consumer demand for automobiles is also growing. When using a vehicle, users may need to navigate narrow, winding areas or navigate around difficult obstacles, which places high demands on the vehicle's steering ability. Steering ability is one of the fundamental attributes of a vehicle, and the minimum turning radius is usually used as an important parameter for evaluating a car's steering capability. Here, the minimum turning radius refers to the radius of the circle traced by the center of the outer steering wheel on a supporting plane (such as the ground) when the steering wheel is turned to its limit and the vehicle is turning at its lowest stable speed. If a vehicle has strong steering capabilities, it can achieve a smaller minimum turning radius, thus enabling it to navigate narrow, winding areas or navigate around difficult obstacles. Summary of the Invention

[0004] Some embodiments of this disclosure provide a steering method, a steering control device, a control system, a computing device, and a vehicle, which can control the first front wheel to be stationary relative to the vehicle and drive the first and second rear wheels of the vehicle to rotate, and control the driving directions of the first and second rear wheels to be opposite, so that the vehicle can turn around the first front wheel. This can achieve vehicle turning around the first front wheel without changing the vehicle's steering system and driving mode, thereby improving the vehicle's steering ability, flexibility, and passability.

[0005] In a first aspect, some embodiments of this disclosure provide a steering method, the method comprising: controlling a first front wheel of a vehicle to be stationary relative to the vehicle; driving a first rear wheel and a second rear wheel of the vehicle to rotate such that the vehicle steers about the first front wheel, wherein the driving directions of the first rear wheel and the second rear wheel are opposite.

[0006] Some embodiments of this disclosure can control the first front wheel to be stationary relative to the vehicle and drive the first and second rear wheels to rotate without changing the vehicle's steering system and drive mode. By controlling the first and second rear wheels to drive in opposite directions, the vehicle can be turned around the first front wheel to achieve steering, which can improve the vehicle's steering ability, flexibility and passability, and better cope with narrow parking environments.

[0007] In one embodiment of the first aspect, controlling the first front wheel to be stationary relative to the vehicle includes:

[0008] The first front wheel is braked and locked to bring it to a standstill relative to the vehicle, or the first front wheel is brought to a standstill relative to the vehicle by torque control. Here, the first front wheel is the front wheel of the vehicle that needs to be stationary.

[0009] In another embodiment of the first aspect, the method further includes: determining, based on steering input information, the first front wheel of the vehicle that needs to be stationary.

[0010] In yet another embodiment of the first aspect, the steering input information is also used to determine at least one of the following: the direction of rotation of the vehicle or the required turning angle of the vehicle.

[0011] In another embodiment of the first aspect, the driving directions of the first and second rear wheels are related to the vehicle's rotation direction. Here, the vehicle's rotation direction is clockwise and counterclockwise.

[0012] In another embodiment of the first aspect, driving the first rear wheel of the vehicle to rotate includes: determining the output torque of the first rear wheel based on the state information of the first rear wheel; and driving the first rear wheel to rotate based on the output torque of the first rear wheel.

[0013] In another embodiment of the first aspect, driving the second rear wheel of the vehicle to rotate includes: determining the output torque of the second rear wheel based on the state information of the second rear wheel; and driving the second rear wheel to rotate based on the output torque of the second rear wheel.

[0014] In another embodiment of the first aspect, the state information of the first rear wheel includes at least one of the wheel speed of the first rear wheel, the wheel acceleration of the first rear wheel, the current slip rate of the first rear wheel, or the target slip rate of the first rear wheel, and the state information of the second rear wheel includes at least one of the wheel speed of the second rear wheel, the wheel acceleration of the second rear wheel, the current slip rate of the second rear wheel, or the target slip rate of the second rear wheel.

[0015] In another embodiment of the first aspect, determining the output torque of the first rear wheel based on the state information of the first rear wheel includes: determining the output torque of the first rear wheel based on the target slip ratio of the first rear wheel, the current slip ratio of the first rear wheel, and the torque control method for the first rear wheel, wherein the output torque of the first rear wheel is used to cause the slip ratio of the first rear wheel to change toward the target slip ratio of the first rear wheel.

[0016] In another embodiment of the first aspect, the method further includes: determining a torque control mode for the first rear wheel based on the wheel speed and wheel acceleration of the first rear wheel.

[0017] In another embodiment of the first aspect, the torque control method for the first rear wheel is used to indicate at least one of the torque adjustment direction for the first rear wheel or the torque adjustment rate for the first rear wheel, wherein the torque adjustment direction is one of increasing torque, decreasing torque, and maintaining torque, and the torque adjustment rate for the first rear wheel is used to indicate the force of adjusting the torque of the first rear wheel.

[0018] In another embodiment of the first aspect, determining the output torque of the second rear wheel based on the state information of the second rear wheel includes: determining the output torque of the second rear wheel based on the target slip ratio of the second rear wheel, the current slip ratio of the second rear wheel, and the torque control method for the second rear wheel, wherein the output torque of the second rear wheel is used to cause the slip ratio of the second rear wheel to change toward the target slip ratio of the second rear wheel.

[0019] In another embodiment of the first aspect, the method further includes: determining a torque control mode for the second rear wheel based on the wheel speed and wheel acceleration of the second rear wheel.

[0020] In another embodiment of the first aspect, the torque control method for the second rear wheel is used to indicate at least one of the torque adjustment direction for the second rear wheel or the torque adjustment rate for the second rear wheel, wherein the torque adjustment direction is one of increasing torque, decreasing torque, and maintaining torque, and the torque adjustment rate for the second rear wheel is used to indicate the force of adjusting the torque of the second rear wheel.

[0021] In yet another embodiment of the first aspect, the method further includes: driving the second front wheel of the vehicle to rotate.

[0022] In another embodiment of the first aspect, driving the second front wheel of the vehicle to rotate includes: determining the output torque of the second front wheel of the vehicle based on the current yaw rate of the vehicle and the target yaw rate of the vehicle; and driving the second front wheel to rotate based on the output torque of the second front wheel, the output torque of the second front wheel being used to cause the yaw rate of the vehicle to change toward the target yaw rate of the vehicle.

[0023] In another embodiment of the first aspect, before the first and second rear wheels of the vehicle are turned, the method further includes:

[0024] Determine if the vehicle meets the rotation conditions; here, the rotation conditions are related to at least one of the following: the maximum output torque of the motor corresponding to the first rear wheel, the maximum output torque of the motor corresponding to the second rear wheel, the reduction ratio of the reducers of the motors corresponding to the first and second rear wheels, the effective rolling radius of the first and second rear wheels, the maximum longitudinal force coefficient between the first rear wheel and the current road surface, the maximum longitudinal force coefficient between the second rear wheel and the current road surface, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the driving force of the second front wheel, the lateral force coefficient of the first rear wheel, the longitudinal force coefficient of the second rear wheel, the lateral force coefficient of the second rear wheel, the track width between the first and second rear wheels, the wheelbase of the vehicle, the rotational resistance of the first front wheel, the moment of inertia of the vehicle, or the angular acceleration of the vehicle.

[0025] In another embodiment of the first aspect, before rotating the first and second rear wheels of the vehicle, the method further includes: determining that the first front wheel satisfies a non-slip condition; wherein the non-slip condition is related to the maximum lateral static friction of the first front wheel, the maximum longitudinal static friction of the first front wheel, the longitudinal force coefficient of the first rear wheel, the lateral force coefficient of the second rear wheel, the longitudinal force coefficient of the second rear wheel, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the reaction force of the driving force of the second front wheel, and the axle design factor of the vehicle, wherein the axle design factor of the vehicle is related to at least one of the track width or the wheelbase of the vehicle, wherein the track width is the distance between the first and second rear wheels.

[0026] In another embodiment of the first aspect, the method further includes: disengaging the vehicle's steering function when the vehicle meets the vehicle's steering disengagement conditions.

[0027] In another embodiment of the first aspect, the vehicle steering disengagement conditions include one or more of the following: the vehicle's rotation angle reaches the vehicle's required rotation angle, the vehicle's user depresses the brake pedal, the vehicle's steering wheel angle exceeds a first threshold, the electronic parking brake is activated, the vehicle's gear is changed, or the vehicle's user deactivates the steering function.

[0028] Secondly, some embodiments of this disclosure provide a steering control device, which includes a processing unit and a drive unit. The processing unit controls the first front wheel of the vehicle to remain stationary relative to the vehicle. The drive unit drives the first and second rear wheels of the vehicle to rotate, so that the vehicle steers about the first front wheel, wherein the first and second rear wheels drive in opposite directions.

[0029] Thirdly, some embodiments of this disclosure provide a control system, which includes a control device and a drive device.

[0030] The control device is configured to keep the first front wheel of the vehicle stationary relative to the vehicle; the drive device is configured to drive the first and second rear wheels of the vehicle to rotate so that the vehicle can be steered about the first front wheel, wherein the first and second rear wheels are driven in opposite directions.

[0031] In one embodiment of the third aspect, the control device includes at least one of a brake or a first motor, wherein, if the control device includes the brake, the brake is used to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle; if the control device includes the first motor, the first motor is used to control the first front wheel to be stationary relative to the vehicle by torque; and if the control device includes the brake and the first motor, the brake is configured to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle, and the first motor is configured to control the first front wheel to be stationary relative to the vehicle by torque.

[0032] In another embodiment of the third aspect, the drive unit includes a second motor and a third motor, the second motor being configured to drive the first rear wheel of the vehicle to rotate, and the third motor being configured to drive the second rear wheel of the vehicle to rotate.

[0033] In yet another embodiment of the third aspect, the first motor is further configured to drive the second front wheel of the vehicle to rotate, or the drive unit further includes a fourth motor configured to drive the second front wheel of the vehicle to rotate.

[0034] In yet another embodiment of the third aspect, the control system further includes a steering controller configured to control the vehicle to steer around the first front wheel.

[0035] In yet another embodiment of the third aspect, the control system is configured to implement the method described in any of the first aspects above.

[0036] Fourthly, some embodiments of this disclosure provide a computing device including a processor and a memory, the memory storing a program, the processor executing the program stored in the memory to cause the computing device to implement the method described in any of the first aspects above.

[0037] Fifthly, some embodiments of this disclosure provide a vehicle that includes a first front wheel, a first rear wheel, a second rear wheel, and the aforementioned steering control device, control system, or computing device.

[0038] In a sixth aspect, some embodiments of this disclosure provide a computer-readable storage medium for storing a computer program including instructions for performing the methods described in any of the first aspects.

[0039] In a seventh aspect, one embodiment provides a computer program product including computer instructions that, when executed by a steering control device or a computing device, cause the steering control device or computing device to implement the method described in any of the first aspects above. Attached Figure Description

[0040] The accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0041] Figure 1 is a flowchart illustrating a steering method according to some embodiments;

[0042] Figure 2 is a schematic diagram of determining the output torque of the first rear wheel according to some embodiments;

[0043] Figure 3 is a schematic diagram of determining a torque control method for the first rear wheel according to some embodiments;

[0044] Figure 4 is a schematic diagram of another method for determining the output torque of the first rear wheel according to some embodiments;

[0045] Figure 5 is a schematic diagram of determining the output torque of the second rear wheel according to some embodiments;

[0046] Figure 6 is a schematic diagram of determining a torque control method for the second rear wheel according to some embodiments;

[0047] Figure 7 is a schematic diagram of another method for determining the output torque of the second rear wheel according to some embodiments;

[0048] Figure 8 is a schematic diagram of determining the output torque of the second front wheel according to some embodiments;

[0049] Figure 9 is a schematic diagram of the longitudinal force coefficient and lateral force coefficient under different slip rates according to some embodiments;

[0050] Figure 10 is a schematic diagram of the forces acting on the four wheels of a vehicle during a steering process according to some embodiments;

[0051] Figure 11 is a schematic diagram of a vehicle leaving the warehouse according to some embodiments;

[0052] Figure 12 is another schematic diagram of a vehicle leaving the warehouse according to some embodiments;

[0053] Figure 13 is a schematic diagram of the architecture of a vehicle according to some embodiments;

[0054] Figure 14 is a schematic diagram of the architecture of a rear-wheel-drive vehicle according to some embodiments;

[0055] Figure 15 is a schematic diagram of the architecture of a distributed three-motor vehicle according to some embodiments;

[0056] Figure 16 is a schematic diagram of the architecture of a four-wheel independent drive vehicle according to some embodiments;

[0057] Figure 17 is a block diagram of a steering control device according to some embodiments;

[0058] Figure 18 is a schematic diagram of the structure of a computing device according to some embodiments. Detailed Implementation

[0059] The following describes some embodiments of this disclosure in detail with reference to the accompanying drawings.

[0060] The following describes some scenarios of embodiments of this disclosure.

[0061] In some scenarios, users may need to navigate narrow, winding areas or bypass insurmountable obstacles when using a vehicle, and may even need the vehicle to steer, which places high demands on the vehicle's steering capabilities.

[0062] In some embodiments, the main type of vehicle with steering function is tracked vehicles or all-wheel steering vehicles with steering mechanisms on each wheel. However, tracked vehicles are only used for special purposes and have a narrow range of applications. All-wheel steering vehicles require the addition of an extra steering system, which requires significant modifications to the steering system and drive method, increasing vehicle cost and the complexity of the mechanical structure.

[0063] To address the aforementioned problems, some embodiments of this disclosure provide a steering method applicable to distributed three-motor vehicles, four-wheel independent drive vehicles, and rear-wheel independent drive vehicles. By controlling the first front wheel to remain stationary relative to the vehicle and driving the first and second rear wheels to rotate, and controlling the driving directions of the first and second rear wheels to be opposite, the vehicle can be steered around the first front wheel. This method enables vehicle steering without changing the vehicle's steering system and drive mode, improving the vehicle's steering ability, flexibility, and passability. It also allows the vehicle to better cope with narrow parking environments, such as enabling side-entry and exit from narrow parking spaces.

[0064] The methods of some embodiments of this disclosure will be described in detail below.

[0065] Referring to Figure 1, in some embodiments, the method can be applied to a vehicle, for example, the method can be applied to a steering control device in a vehicle.

[0066] The turning method shown in Figure 1 may include multiple steps in steps S101 to S102. It should be understood that, for ease of description, the method is described in the order of steps S101 to S102, and is not intended to limit the execution to this specific order. This disclosure does not limit the order of execution, the execution time, or the number of executions of the above one or more steps. For example, steps S101 to S102 are as follows:

[0067] Step S101: Keep the first front wheel of the vehicle stationary relative to the vehicle.

[0068] In some embodiments, the steering control device controls the first front wheel to remain stationary relative to the vehicle. For example, the steering control device controls the first front wheel to remain stationary relative to the vehicle's support structure.

[0069] A steering control device is a device with data processing, communication, and control capabilities. It may be located inside a vehicle or integrated into a processing module within the vehicle. For example, the steering control device may be at least one of a microcontroller unit (MCU) or an electronic control unit (ECU). In some embodiments, the steering control device may also be located outside the vehicle; for example, it may be a server, cloud, or host computer, or it may be a virtual device, such as a virtual machine, software, program code, or container. In some embodiments, when the steering control device is installed in a vehicle, the functions implemented by the steering control device can also be considered to be implemented by the vehicle. For example, when the steering control device is installed in a vehicle, it can be a functional module, such as being integrated into the vehicle's central domain controller.

[0070] The vehicle is a vehicle with independent rear wheel drive capability provided in some embodiments of this disclosure. The vehicle can be a distributed three-motor vehicle, a four-wheel independent drive vehicle, or a rear wheel independent drive vehicle, etc. The vehicle includes a first front wheel, a first rear wheel, and a second rear wheel.

[0071] The first front wheel is the front wheel selected by the user to be stationary. In some embodiments, the steering control device can control the first front wheel to remain stationary relative to the vehicle by braking and locking the first front wheel. For example, the steering control device can output a control signal to the braking system, instructing the braking system to brake and lock the first front wheel to keep it stationary relative to the vehicle. This coordinates the vehicle's braking system, facilitating control of the vehicle to maintain the position of the first front wheel during steering, thus improving the precision of the steering process.

[0072] Here, brake lock-up refers to the phenomenon where, when a car brakes, the wheels stop rotating after being subjected to strong braking force, but due to the inertia generated by the car's speed, the car continues to slide forward even after the wheels have stopped rotating.

[0073] In other embodiments, if the vehicle is a distributed three-motor vehicle or a four-wheel independently driven vehicle, the steering control device can also control the output torque of the motor corresponding to the first front wheel to keep the first front wheel stationary relative to the vehicle by controlling the output torque of the motor corresponding to the first front wheel through the drive system. For example, the steering control device can output a control signal to the drive system, which instructs the drive system to control the output torque of the motor corresponding to the first front wheel to keep the first front wheel stationary relative to the vehicle.

[0074] In this way, coordinating the vehicle's drive system makes it easier to control the vehicle to keep the position of the first front wheel unchanged during steering, thus improving the precision of the steering process.

[0075] In some embodiments of this disclosure, the steering control device controls the first and second rear wheels to drive in opposite directions. Generally, because the first and second rear wheels drive in opposite directions, the driving forces of the first and second rear wheels can counteract most of the longitudinal forces of the vehicle. When using the drive system to control the output torque of the motor corresponding to the first front wheel to keep the first front wheel stationary, only a small output torque is needed to keep the first front wheel and the vehicle relatively stationary. Here, longitudinal refers to the direction of vehicle movement or travel.

[0076] In some embodiments, the output torque of the motor corresponding to the first front wheel is obtained by weighting the difference in motor torque between the two rear wheels (e.g., the first rear wheel and the second rear wheel) with a target wheel speed lookup table using a proportional-integral-derivative (PID) control algorithm.

[0077] In some embodiments, the output torque of the motor corresponding to the first front wheel satisfies the following formula (1): Trq F = αβ△Trq R +(1-α)×PID F (1)

[0078] Among them, Trq F ΔTrq represents the output torque of the motor corresponding to the first front wheel of the vehicle, α is a weighting coefficient, β is a torque adjustment coefficient (usually a negative value), and ΔTrq is the torque output torque of the motor corresponding to the first front wheel of the vehicle. R The difference in output torque between the motors of the two rear wheels of the vehicle, PID F This is the torque value output by the PID controller for the first front wheel of the vehicle, obtained by looking up the table.

[0079] When the steering function is engaged and the rear wheel torque does not cause the rear wheels to slip, the weighting coefficient α is 1. At this time, the difference in torque between the two rear wheel motors is used to adjust the output torque of the motor corresponding to the first front wheel to keep the first front wheel stationary relative to the vehicle. When the output torque of the two rear wheel motors causes the two rear wheels to slip, the weighting coefficient α gradually changes from 1 to 0. At this time, the output torque of the motor corresponding to the first front wheel is adjusted by looking up the target wheel speed in a PID control table to keep the first front wheel stationary relative to the vehicle. When the steering function is disengaged, the two rear wheels change from a slipping state to a non-slipping state, and the weighting coefficient α gradually changes from 0 to 1. At this time, the output torque of the motor corresponding to the first front wheel is adjusted by looking up the target wheel speed in a PID control table to keep the first front wheel stationary relative to the vehicle.

[0080] In some embodiments, the output torque of the motor corresponding to the first front wheel is obtained by weighting the difference in torque between the two rear motors with the target wheel speed using a lookup table PID controller, so that the first front wheel is kept stationary relative to the vehicle. Alternatively, other control methods such as incremental PID or slipform variable control can be used to control the output torque of the motor corresponding to the first front wheel so that the first front wheel is kept stationary relative to the vehicle.

[0081] In some embodiments, before executing step S101, the steering control device may acquire steering input information and determine, based on the steering input information, the front wheels of the vehicle that need to be stationary. Further, the steering control device may also determine one or more of the vehicle's rotation direction or the required rotation angle. Here, the vehicle's rotation direction includes clockwise rotation and counterclockwise rotation. In some embodiments, the steering input information is input by the user; for example, the user selects the left front wheel as the front wheel that the vehicle needs to be stationary and selects that the vehicle rotate 180° counterclockwise around the left front wheel.

[0082] It should be noted that during steering, the stationary front wheels will serve as the vehicle's center of rotation, and the steering effect will vary depending on which stationary front wheels are selected.

[0083] In some embodiments, the first front wheel can be determined in multiple ways; that is, the user or vehicle can select the front wheel that needs to be stationary through various methods. The methods for determining the first front wheel include, but are not limited to, one or more of the following: vehicle-mounted system selection, button selection, remote control selection, or steering wheel selection. In some embodiments, the user can directly select the front wheel that needs to be stationary (i.e., the vehicle's rotation center) through vehicle-mounted system selection, button selection, or remote control selection. For example, the user can select the left front wheel as the front wheel that needs to be stationary through a button. In other embodiments, the user selects the front wheel that needs to be stationary through the steering wheel. For example, if the driver turns the steering wheel clockwise and the steering wheel angle reaches a second threshold, the right front wheel is selected as the front wheel that needs to be stationary; or, if the driver turns the steering wheel counterclockwise and the steering wheel angle reaches a third threshold, the left front wheel is selected as the front wheel that needs to be stationary and braked to lock. It should be noted that the second and third thresholds can be preset values ​​or values ​​manually set by the user.

[0084] In some embodiments, after the user selects the front wheel that needs to be stationary, the steering control device displays the user's selection information on the vehicle's infotainment system. For example, the system may display "The user has selected the left front wheel as the front wheel that needs to be stationary," or it may display a rotation diagram with the rotation center marked, which is the selected first front wheel. Alternatively, if the user can set a second threshold of 100° in the settings interface, the left front wheel will be the front wheel that needs to be stationary when the user turns the steering wheel more than 100° to the left. This allows for the selection of the stationary front wheel in multiple ways, improving steering precision.

[0085] In some embodiments, the rotation direction of the vehicle can be determined in a variety of ways, including but not limited to one or more of the following: vehicle-mounted system selection, button selection, remote control selection, or gear selection.

[0086] In some embodiments, the user can directly select the vehicle's rotation direction via in-vehicle infotainment system, button selection, or remote control selection. For example, the user can select clockwise rotation via the in-vehicle infotainment system. In other embodiments, the vehicle's rotation direction is selected via gear selection; for example, the driver can select the vehicle's rotation direction using D (Drive) or R (Reverse). For instance, the driver can select clockwise rotation using R and counterclockwise rotation using D.

[0087] In some embodiments, after the user selects the vehicle's rotation direction, the steering control device displays the user's selection information on the vehicle's infotainment system. For example, the system may display "The user has selected the vehicle's rotation direction as clockwise," or it may display a rotation diagram indicating the rotation direction. This allows for selection of the vehicle's rotation direction in multiple ways, improving steering accuracy.

[0088] In some embodiments, the required turning angle of the vehicle can be determined in various ways, including but not limited to one or more of the following: vehicle-mounted system selection, button selection, remote control selection, or steering wheel selection. In some embodiments, the user can directly select the required turning angle of the vehicle through vehicle-mounted system selection, button selection, or remote control selection. For example, the user selects the required turning angle of the vehicle as 180° through a button. In some embodiments, after the user selects the required turning angle of the vehicle, the steering control device displays the user's selection information on the vehicle-mounted system. For example, the vehicle-mounted system displays "The user has selected a required turning angle of 180°," or, for another example, the vehicle-mounted system displays a rotation diagram, indicating the direction and position of the vehicle after rotation.

[0089] Step S102: Drive the first and second rear wheels of the vehicle to rotate so that the vehicle can steer around the first front wheel.

[0090] Here, the first and second rear wheels drive in opposite directions, and their driving directions are related to the vehicle's rotation direction. In some embodiments, the steering control device drives the first rear wheel to rotate based on the output torque of the first rear wheel, and drives the second rear wheel to rotate based on the output torque of the second rear wheel.

[0091] In some embodiments, the first rear wheel is the left rear wheel and the second rear wheel is the right rear wheel. When the vehicle rotates clockwise, the first rear wheel is driven forward, and the second rear wheel is driven backward. The steering control device drives the first rear wheel forward based on the output torque of the first rear wheel and drives the second rear wheel backward based on the output torque of the second rear wheel, so that the vehicle can be turned clockwise around the first front wheel.

[0092] In other embodiments, the first rear wheel is the right rear wheel and the second rear wheel is the left rear wheel. When the vehicle rotates clockwise, the first rear wheel is driven rearward, and the second rear wheel is driven forward. The steering control device drives the first rear wheel backward based on the output torque of the first rear wheel and drives the second rear wheel forward based on the output torque of the second rear wheel, so that the vehicle can be turned clockwise around the first front wheel.

[0093] In some embodiments, the first rear wheel is the left rear wheel and the second rear wheel is the right rear wheel. When the vehicle rotates counterclockwise, the first rear wheel is driven backward, and the second rear wheel is driven forward. The steering control device drives the first rear wheel backward based on the output torque of the first rear wheel and drives the second rear wheel forward based on the output torque of the second rear wheel, so that the vehicle can turn counterclockwise around the first front wheel.

[0094] In some other embodiments, the first rear wheel is the right rear wheel and the second rear wheel is the left rear wheel. When the vehicle rotates counterclockwise, the first rear wheel is driven forward, and the second rear wheel is driven backward. The steering control device drives the first rear wheel forward based on the output torque of the first rear wheel and drives the second rear wheel backward based on the output torque of the second rear wheel, so that the vehicle can turn counterclockwise around the first front wheel.

[0095] In some embodiments, the vehicle steers around the first front wheel, which can also be described as the vehicle having the ability to turn on the spot, which can improve the vehicle's flexibility and passability, and better cope with narrow parking environments.

[0096] The following describes one possible implementation method for determining the output torque of the first rear wheel.

[0097] In some embodiments, the steering control device determines the output torque of the first rear wheel based on the state information of the first rear wheel.

[0098] Here, the first rear wheel and the first front wheel are located on the same side of the vehicle. The state information of the first rear wheel includes at least one of the following: wheel speed, wheel acceleration, current slip ratio, or target slip ratio. The output torque of the first rear wheel is used to cause its slip ratio to change towards the target slip ratio. It should be understood that during vehicle steering, the "steering control device determines the output torque of the first rear wheel based on the state information of the first rear wheel" can be executed in real time and multiple times, thereby updating the output torque of the first rear wheel in real time during steering to control the first rear wheel and thus complete the vehicle's rotation.

[0099] In some embodiments, the steering control device acquires the wheel speed of the first rear wheel via a wheel speed sensor, obtains the wheel acceleration and current slip ratio of the first rear wheel based on the wheel speed, and determines a torque control mode for the first rear wheel based on the wheel speed and wheel acceleration. Further, the steering control device determines the output torque of the first rear wheel based on the target slip ratio, the current slip ratio, and the torque control mode. Here, the torque control mode for the first rear wheel indicates at least one of the torque adjustment direction or the torque adjustment rate for the first rear wheel. The torque adjustment direction is one of increasing torque (or increasing torque, raising torque), decreasing torque (or reducing torque, lowering torque), and maintaining torque. The torque adjustment rate for the first rear wheel indicates the force of adjusting the torque of the first rear wheel. Here, maintaining torque means keeping the torque constant.

[0100] In some embodiments, as shown in FIG2, the steering control device compares the current slip ratio (e.g., s1) of the first rear wheel with the target slip ratio (e.g., s2) of the first rear wheel to obtain the slip ratio difference (e.g., Δs1, also referred to as the slip ratio difference Δs1 of the first rear wheel) between the current slip ratio and the target slip ratio of the first rear wheel. Further, the steering control device uses the slip ratio difference (e.g., Δs1) of the first rear wheel as the input to segmented PID control. Based on the wheel speed and wheel acceleration of the first rear wheel, the steering control device determines the torque control method for the first rear wheel and uses this torque control method as the basis for segmented PID control, that is, it uses the torque control method for the first rear wheel as the enable flag for segmented PID control jumps, outputting the output torque of the first rear wheel. Here, the enabling function allows a certain pin, chip, or module of the electronic device to activate a preset function or enter a preset state.

[0101] In some embodiments, the torque control method for the first rear wheel is divided into five stages: the five stages are: high-speed torque increase stage, low-speed torque increase stage, stabilization stage, low-speed torque decrease stage, and high-speed torque decrease stage.

[0102] In some embodiments, when the first rear wheel is in a high-speed torque increase phase, the current enable flag can be "high-speed torque increase," corresponding to an increasing torque adjustment direction. High speed corresponds to a larger torque adjustment force, such as outputting a larger output torque in segmented PID control, causing the slip ratio of the first rear wheel to increase rapidly, moving towards the target slip ratio. In other embodiments, when the first rear wheel is in a low-speed torque decrease phase, the current enable flag can be "low-speed torque decrease," corresponding to a decreasing torque adjustment direction. Low speed corresponds to a smaller torque adjustment force, such as outputting a smaller output torque in segmented PID control, causing the slip ratio of the first rear wheel to decrease slowly, moving towards the target slip ratio.

[0103] In some embodiments, as shown in Figure 3, when the wheel speed of the first rear wheel is less than a first wheel speed threshold, the torque control method for the first rear wheel is a high-rate torque increase phase, in which case the wheel speed of the first rear wheel needs to be increased as quickly as possible. When the wheel speed of the first rear wheel does not meet the requirement of being less than the first wheel speed threshold, then when the wheel speed of the first rear wheel is less than a second wheel speed threshold, the torque control method for the first rear wheel is a low-rate torque increase phase, in which case the wheel speed of the first rear wheel needs to be increased slowly. When the wheel speed of the first rear wheel does not meet the requirement of being less than the second wheel speed threshold, then when the wheel speed of the first rear wheel is greater than a third wheel speed threshold and the wheel acceleration of the first rear wheel is less than the first wheel acceleration threshold, the torque control method for the first rear wheel is a stable control phase, in which case the wheel speed of the first rear wheel needs to be kept stable. If the wheel speed of the first rear wheel does not meet the requirement of being greater than the third wheel speed threshold and the wheel acceleration of the first rear wheel does not meet the requirement of being less than the first wheel acceleration threshold, then when the wheel speed of the first rear wheel is greater than the third wheel speed threshold and the wheel acceleration of the first rear wheel is greater than the first wheel acceleration threshold, the torque control mode for the first rear wheel is a low-rate torque reduction phase, in which case the wheel speed of the first rear wheel needs to be reduced slowly. If the wheel speed of the first rear wheel does not meet the requirement of being greater than the third wheel speed threshold and the wheel acceleration of the first rear wheel does not meet the requirement of being greater than the first wheel acceleration threshold, then when the wheel speed of the first rear wheel is greater than the fourth wheel speed threshold and the wheel acceleration of the first rear wheel is greater than the second wheel acceleration threshold, the torque control mode for the first rear wheel is a high-rate torque reduction phase, in which case the wheel speed of the first rear wheel needs to be reduced as quickly as possible. Here, the first wheel speed threshold, second wheel speed threshold, third wheel speed threshold, fourth wheel speed threshold, first wheel acceleration threshold, and second wheel acceleration threshold can all be preset values ​​or user-selected values.

[0104] In some embodiments, during steering, when the vehicle rotates clockwise, the left rear motor outputs positive torque, causing the left rear wheel to slide forward and generate a forward driving force; the right rear motor outputs negative torque, causing the right rear wheel to slide in reverse and generate a rearward driving force. When the vehicle rotates counterclockwise, the left rear motor outputs negative torque, causing the left rear wheel to slide in reverse and generate a rearward driving force; the right rear motor outputs positive torque, causing the right rear wheel to slide forward and generate a forward driving force.

[0105] Since one of the two rear wheels slips in the forward direction and the other slips in the reverse direction, the longitudinal forces generated by the two rear wheels cancel each other out, and the first front wheel is controlled to be stationary relative to the vehicle, the method in some embodiments of this disclosure ensures that the vehicle will not move longitudinally during steering, so that the driver does not have to worry about the vehicle moving longitudinally and can improve steering accuracy.

[0106] It should be noted that for the vehicle to steer, the first rear wheel needs to reach a preset slip ratio. Since the driving force will decrease significantly after the tire grip reaches its limit, the output torque of the first rear wheel needs to be controlled during the control process to prevent the first rear wheel from spinning out of control.

[0107] It should be noted that the above-mentioned segmented PID control can quickly eliminate the integral term, avoiding excessive integral terms and improving system stability. Furthermore, because segmented PID control is used, the control algorithm can obtain the optimal control stage based on the current wheel speed and acceleration of the first rear wheel. This allows the control strategy to better adapt to different road conditions, improving the accuracy of first rear wheel control during vehicle steering. It also controls the slip ratio of the first rear wheel towards the target slip ratio, thereby maintaining a stable wheel speed and improving steering safety.

[0108] Here, the integral term is the accumulated sum of errors, used to eliminate the static error of the control system. When the road surface adhesion is uniform, both ordinary PID and piecewise PID can achieve good control results. The purpose of using piecewise PID here is to deal with situations where the slip rate (or wheel speed) of the first rear wheel is difficult to reach a steady state when the road surface adhesion changes abruptly. For example, when the road surface adhesion suddenly decreases significantly, the integral term of an ordinary PID can only slowly decrease by accumulating the error, which may lead to sudden slippage of the first rear wheel and obvious vehicle jerking. However, when using piecewise PID, the current control stage can be obtained based on the current wheel speed and wheel speed difference of the first rear wheel. By jumping between stages (and adjusting the PID control parameters), the integral term can be quickly reduced or cleared, avoiding sudden slippage of the wheel speed of the first rear wheel and vehicle jerking, thus improving the robustness of the system.

[0109] Of course, other control methods can also be used. The core control idea is to control the current slip ratio of the first rear wheel to be close to the target slip ratio of the first rear wheel, that is, to control the current slip ratio of the first rear wheel to change towards the target slip ratio of the first rear wheel, or to control the current wheel speed of the first rear wheel to be close to the target wheel speed of the first rear wheel, that is, to control the current wheel speed of the first rear wheel to change towards the target wheel speed of the first rear wheel.

[0110] In some embodiments, in determining the output torque of the first rear wheel, in addition to the state information of the first rear wheel, other information, such as the vehicle's yaw rate, may also be used. Some possible implementations are described below.

[0111] In some embodiments, the steering control device can also determine the output torque of the first rear wheel based on the state information of the first rear wheel, the current yaw rate of the vehicle, and the target yaw rate of the vehicle. For example, as shown in FIG4, the steering control device compares the current slip ratio (e.g., s1) of the first rear wheel with the target slip ratio (e.g., s2) of the first rear wheel to obtain the slip ratio difference between the current slip ratio and the target slip ratio of the first rear wheel (e.g., Δs1, which can also be referred to as the slip ratio difference Δs1 of the first rear wheel), and compares the current yaw rate (e.g., w1) of the vehicle with the target yaw rate (e.g., w2) of the vehicle to obtain the yaw rate difference between the current yaw rate and the target yaw rate of the vehicle (e.g., Δw, which can also be referred to as the yaw rate difference Δw). Furthermore, the steering control unit uses the slip ratio difference (e.g., Δs1) and yaw rate difference (e.g., Δw) of the first rear wheels as inputs to the segmented PID control. Based on the wheel speed and acceleration of the first rear wheels, the steering control unit determines the torque control method for the first rear wheels and uses this method as the basis for the segmented PID control; that is, it uses the torque control method for the first rear wheels as the enable flag for the segmented PID control to switch, and outputs the output torque of the first rear wheels. Here, the torque control method for the first rear wheels is described in the aforementioned related description. The target yaw rate of the vehicle can be a default initial value or can be set and selected by the driver.

[0112] It should be noted that the above-mentioned segmented PID control can quickly eliminate the integral term, avoid excessive integral term, and improve system stability. Furthermore, due to the segmented PID control, the control algorithm can obtain the optimal control stage based on the current wheel speed and wheel acceleration of the first rear wheel, allowing the control strategy to better adapt to different road conditions. Of course, other control methods can also be used. The calculation of yaw moment is not limited to PID control; other control methods can also be employed. The goal is simply to generate yaw moment to stabilize the vehicle body, and control the current slip ratio of the first rear wheel to be close to the target slip ratio of the first rear wheel, and control the current yaw rate of the vehicle to be close to the target yaw rate. In other words, control the current slip ratio of the first rear wheel to change towards the target slip ratio of the first rear wheel, and control the current yaw rate of the vehicle to change towards the target yaw rate.

[0113] The following describes one possible implementation method for determining the output torque of the second rear wheel.

[0114] In some embodiments, the steering control device determines the output torque of the second rear wheel based on the state information of the second rear wheel.

[0115] Here, the second rear wheel is located on the opposite side of the vehicle from the first rear wheel. The state information of the second rear wheel includes at least one of the following: wheel speed, wheel acceleration, current slip ratio, or target slip ratio. The output torque of the second rear wheel is used to cause its slip ratio to change towards the target slip ratio. In some embodiments, the target slip ratio of the second rear wheel may be the same as or different from the target slip ratio of the first rear wheel. It should be understood that during vehicle steering, the process of "determining the output torque of the second rear wheel based on its state information" can be executed in real time and multiple times, thereby updating the output torque of the second rear wheel in real time during steering to control the second rear wheel and thus complete the vehicle's rotation.

[0116] In some embodiments, the steering control device acquires the wheel speed of the second rear wheel via a wheel speed sensor, obtains the wheel acceleration and current slip ratio of the second rear wheel based on the wheel speed, and determines a torque control mode for the second rear wheel based on the wheel speed and wheel acceleration. Further, the steering control device determines the output torque of the second rear wheel based on the target slip ratio, the current slip ratio, and the torque control mode. Here, the torque control mode for the second rear wheel indicates at least one of the torque adjustment direction or the torque adjustment rate for the second rear wheel. The torque adjustment direction is one of increasing torque (or increasing torque, raising torque), decreasing torque (or reducing torque, lowering torque), and maintaining torque. The torque adjustment rate for the second rear wheel indicates the force of adjusting the torque of the second rear wheel. Here, maintaining torque means keeping the torque constant.

[0117] In some embodiments, as shown in FIG5, the steering control device compares the current slip ratio of the second rear wheel (e.g., s3) with the target slip ratio of the second rear wheel (e.g., s4) to obtain the slip ratio difference between the current slip ratio of the second rear wheel and the target slip ratio of the second rear wheel (e.g., Δs2, which can also be referred to as the slip ratio difference Δs2 of the second rear wheel). Further, the steering control device uses the slip ratio difference of the second rear wheel (e.g., Δs2) as the input to segmented PID control. Based on the wheel speed and wheel acceleration of the second rear wheel, the steering control device determines the torque control mode for the second rear wheel and uses this torque control mode as the basis for segmented PID control, that is, it uses the torque control mode for the second rear wheel as the enable flag for segmented PID control jumps, and outputs the output torque of the second rear wheel.

[0118] In some embodiments, the torque control method for the second rear wheel is divided into five stages: high-speed torque increase stage, low-speed torque increase stage, stabilization stage, low-speed torque decrease stage, and high-speed torque decrease stage.

[0119] In some embodiments, when the second rear wheel is in a high-speed torque-increasing phase, the current enable flag can be "high-speed torque increase," corresponding to an increasing torque adjustment direction. High speed corresponds to a larger torque adjustment force, such as outputting a larger output torque in segmented PID control, causing the slip ratio of the second rear wheel to increase rapidly, moving towards the target slip ratio. In other embodiments, when the second rear wheel is in a low-speed torque-decreasing phase, the current enable flag can be "low-speed torque decrease," corresponding to a decreasing torque adjustment direction. Low speed corresponds to a smaller torque adjustment force, such as outputting a smaller output torque in segmented PID control, causing the slip ratio of the second rear wheel to decrease slowly, moving towards the target slip ratio.

[0120] In some embodiments, as shown in Figure 6, when the wheel speed of the second rear wheel is less than the fifth wheel speed threshold, the torque control method for the second rear wheel is a high-rate torque increase phase, in which case the wheel speed of the second rear wheel needs to be increased as quickly as possible. When the wheel speed of the second rear wheel does not meet the requirement of being less than (e.g., greater than or equal to) the fifth wheel speed threshold, then when the wheel speed of the second rear wheel is less than the sixth wheel speed threshold, the torque control method for the second rear wheel is a low-rate torque increase phase, in which case the wheel speed of the second rear wheel needs to be increased slowly. When the wheel speed of the second rear wheel does not meet the requirement of being less than (e.g., greater than or equal to) the sixth wheel speed threshold, then when the wheel speed of the second rear wheel is greater than the seventh wheel speed threshold and the wheel acceleration of the second rear wheel is less than the third wheel acceleration threshold, the torque control method for the second rear wheel is a stable control phase, in which case the wheel speed of the second rear wheel needs to be kept stable. If the second rear wheel speed does not meet the condition of being greater than (e.g., less than or equal to) the seventh wheel speed threshold and the second rear wheel acceleration does not meet the condition of being less than (e.g., greater than or equal to) the third wheel acceleration threshold, then when the second rear wheel speed is greater than the seventh wheel speed threshold and the second rear wheel acceleration is greater than the third wheel acceleration threshold, the torque control mode for the second rear wheel is a low-rate torque reduction phase, in which case the wheel speed of the second rear wheel needs to be reduced slowly. If the second rear wheel speed does not meet the condition of being greater than (e.g., less than or equal to) the seventh wheel speed threshold and the second rear wheel acceleration does not meet the condition of being greater than (e.g., less than or equal to) the third wheel acceleration threshold, then when the second rear wheel speed is greater than the eighth wheel speed threshold and the second rear wheel acceleration is greater than the fourth wheel acceleration threshold, the torque control mode for the second rear wheel is a high-rate torque reduction phase, in which case the wheel speed of the second rear wheel needs to be reduced as quickly as possible.

[0121] Here, the fifth, sixth, seventh, and eighth round speed thresholds, as well as the third and fourth round acceleration thresholds, can all be preset values ​​or user-selected values. The fifth round speed threshold can be the same as the aforementioned first round speed threshold, the sixth round speed threshold can be the same as the aforementioned second round speed threshold, the seventh round speed threshold can be the same as the aforementioned third round speed threshold, the eighth round speed threshold can be the same as the aforementioned fourth round speed threshold, the third round acceleration threshold can be the same as the aforementioned first round acceleration threshold, and the fourth round acceleration threshold can be the same as the aforementioned second round acceleration threshold.

[0122] In some embodiments, during steering, when the vehicle rotates clockwise, the left rear motor outputs positive torque, causing the left rear wheel to slide forward and generate a forward driving force; the right rear motor outputs negative torque, causing the right rear wheel to slide in reverse and generate a rearward driving force. When the vehicle rotates counterclockwise, the left rear motor outputs negative torque, causing the left rear wheel to slide in reverse and generate a rearward driving force; the right rear motor outputs positive torque, causing the right rear wheel to slide forward and generate a forward driving force.

[0123] It should be noted that for the vehicle to steer, the second rear wheel needs to reach a preset slip ratio. Since the driving force will decrease significantly after the tire grip reaches its limit, the output torque of the second rear wheel needs to be controlled during the control process to prevent the second rear wheel from spinning out of control.

[0124] It should be noted that the above-mentioned piecewise PID control can quickly eliminate the integral term, avoiding excessive integral terms and improving system stability. Furthermore, because piecewise PID control is used, the control algorithm can obtain the optimal control stage based on the current wheel speed and acceleration of the second rear wheel, allowing the control strategy to better adapt to different road conditions. This improves the accuracy of second rear wheel control during steering and controls the slip ratio of the second rear wheel towards the target slip ratio, thereby maintaining the stability of the second rear wheel and improving vehicle steering safety. Here, the integral term is the cumulative sum of errors, used to eliminate static errors in the control system. When road surface adhesion is uniform, both ordinary PID and piecewise PID can achieve good control results. The purpose of using piecewise PID here is to address situations where the slip ratio (or wheel speed) of the second rear wheel is difficult to reach a steady state when road surface adhesion changes abruptly. For example, when road surface adhesion suddenly decreases significantly, the integral term of an ordinary PID can only slowly decrease by accumulating errors, which may lead to sudden wheel slippage and significant vehicle jerking. However, when using segmented PID, the current control stage can be obtained based on the current wheel speed and wheel speed difference of the second rear wheel. By switching stages (and adjusting the PID control parameters), the integral term can be quickly reduced or cleared to avoid sudden increases in the wheel speed of the second rear wheel and vehicle jerking, thus improving the robustness of the system.

[0125] Of course, other control methods can also be used, such as controlling the current slip ratio of the second rear wheel to be close to the target slip ratio of the second rear wheel, that is, controlling the current slip ratio of the second rear wheel to change towards the target slip ratio of the second rear wheel, or controlling the current wheel speed of the second rear wheel to be close to the target wheel speed of the second rear wheel, that is, controlling the current wheel speed of the second rear wheel to change towards the target wheel speed of the second rear wheel.

[0126] In some embodiments, in determining the output torque of the second rear wheel, in addition to the state information of the second rear wheel, other information, such as the vehicle's yaw rate, may also be used. Some possible implementations are described below.

[0127] In some embodiments, the steering control device can also determine the output torque of the second rear wheel based on the state information of the second rear wheel, the current yaw rate of the vehicle, and the target yaw rate of the vehicle. In some embodiments, as shown in FIG7, the steering control device compares the current slip ratio of the second rear wheel (e.g., s3) with the target slip ratio of the second rear wheel (e.g., s4) to obtain the slip ratio difference between the current slip ratio of the second rear wheel and the target slip ratio of the second rear wheel (e.g., Δs2, which can also be referred to as the slip ratio difference Δs2 of the second rear wheel), and compares the current yaw rate of the vehicle (e.g., w1) with the target yaw rate of the vehicle (e.g., w2) to obtain the yaw rate difference between the current yaw rate of the vehicle and the target yaw rate of the vehicle (e.g., Δw, which can also be referred to as the yaw rate difference Δw). Furthermore, the steering control unit uses the slip ratio difference (e.g., Δs2) and yaw rate difference (e.g., Δw) of the second rear wheels as inputs to the segmented PID control. Based on the wheel speed and wheel acceleration of the second rear wheels, the steering control unit determines the torque control method for the second rear wheels and uses this method as the basis for the segmented PID control; that is, it uses the torque control method for the second rear wheels as the enable flag for segmented PID control switching, outputting the output torque of the second rear wheels. The torque control method for the second rear wheels is described in the aforementioned related description. The target yaw rate of the vehicle can be a default initial value or can be set and selected by the driver.

[0128] It should be noted that the above-mentioned segmented PID control can quickly eliminate the integral term, avoiding excessive integral terms and improving system stability. Furthermore, due to the segmented PID control, the control algorithm can obtain the optimal control stage based on the current wheel speed and acceleration of the second rear wheel, allowing the control strategy to better adapt to different road conditions. Of course, other control methods can also be used. The calculation of yaw moment is not limited to PID control; other control methods can also be employed, as long as the yaw moment is generated to stabilize the vehicle body, and the current slip rate of the second rear wheel is controlled to be near the target slip rate of the second rear wheel, and the current yaw rate of the vehicle is controlled to be near the target yaw rate. In other words, the current slip rate of the second rear wheel is controlled to change towards the target slip rate of the second rear wheel, and the current yaw rate of the vehicle is controlled to change towards the target yaw rate.

[0129] In some embodiments, the above description is for the purpose of detailing the calculation process of the output torque of each wheel, so the determination process of the output torque of each wheel is introduced separately. In actual use, the steering control device can calculate and output the output torque of the first rear wheel, the output torque of the second rear wheel, and the output torque of the second front wheel in a segmented PID control according to the input of each wheel.

[0130] In some embodiments, once the vehicle's rotation angle reaches the required rotation angle, the steering control device controls the vehicle to stop steering.

[0131] For example, during steering, the vehicle's rotation angle needs to be recorded in real time. When the rotation angle is about to reach the required rotation angle of the vehicle, the steering function will perform a pre-disengagement process. The steering control device integrates the yaw rate output by the yaw rate sensor to obtain the vehicle's rotation angle. For example, the vehicle's rotation angle satisfies the following formula (2):

[0132] Where, θ yaw Let t be the vehicle's rotation angle, t be the duration of the steering, and w be the steering angle. i T is the real-time yaw rate of the vehicle. i This represents the sampling time step.

[0133] In some embodiments, when the vehicle meets the steering exit condition, the steering control device controls the vehicle to disengage from the steering function. For example, the steering control device controls the motor corresponding to the first rear wheel to slowly unload its output torque, and controls the motor corresponding to the second rear wheel to slowly unload its output torque. When the output torque of the first and second rear wheels drops below a torque threshold, the braking pressure of the first front wheel is released, thus releasing the brake lock of the first front wheel. If the first front wheel is stationary using torque control, the motor corresponding to the first front wheel is controlled to slowly unload its output torque, and the vehicle exits the steering function. If the vehicle does not meet the steering exit condition, the steering control device controls the vehicle to continue steering around the first front wheel. Here, the torque threshold is a preset value.

[0134] In some embodiments, during the process of the vehicle starting to turn, the steering control device controls the motors corresponding to the first and second rear wheels to increase slowly, and during the process of the vehicle exiting the turn, the steering control device controls the motors corresponding to the first and second rear wheels to decrease slowly, so as to reduce the jerking sensation when the vehicle starts to turn and exits the turn.

[0135] In some embodiments, the vehicle's steering disengagement conditions include the vehicle's rotation angle reaching the required rotation angle, the driver depressing the brake pedal, the vehicle's steering wheel angle exceeding a first threshold, activation of the electronic parking brake (EPB), a gear shift, and the driver deactivating the steering function. Here, the first threshold can be a default initial value or can be set and selected by the driver. Thus, once the vehicle meets the steering disengagement conditions, such as the driver depressing the brake pedal or turning the steering wheel angle beyond a preset angle, the vehicle's steering immediately disengages, further ensuring vehicle controllability.

[0136] In a distributed three-motor vehicle, one of the motors can drive the left and right front wheels. In a four-wheel independent drive vehicle, the left and right front wheels can be driven independently.

[0137] In some embodiments, for both types of vehicles, the vehicle includes a second front wheel, which can be driven to rotate by a steering control device.

[0138] In some embodiments, the second front wheel is located on the same side of the vehicle as the aforementioned second rear wheel. The steering control device can determine the output torque of the second front wheel based on the vehicle's current yaw rate and the vehicle's target yaw rate, and drive the second front wheel to rotate based on the output torque of the second front wheel. Here, the output torque of the second front wheel is used to cause the vehicle's yaw rate to change toward the vehicle's target yaw rate.

[0139] In some embodiments, as shown in FIG8, the steering control device compares the vehicle's current yaw rate (e.g., w1) with the vehicle's target yaw rate (e.g., w2) to obtain a yaw rate difference (e.g., Δw, also referred to as the yaw rate difference Δw) between the vehicle's current yaw rate and the vehicle's target yaw rate. Further, the steering control device uses the yaw rate difference (e.g., Δw) as input to a piecewise PID control, outputting the output torque of the second front wheel. Thus, this disclosure can generate a yaw torque, controlling the vehicle's current yaw rate to change towards the vehicle's target yaw rate, with the second front wheel controlling the stability of the vehicle's yaw rate, making the vehicle more stable and controllable during steering, and improving steering safety.

[0140] In the method shown in Figure 8, segmented PID control is used. This method can quickly eliminate the integral term, avoid excessively large integral terms, and improve system stability. Of course, other control methods can also be used. The calculation of yaw moment is not limited to PID control; other control methods can also be used. The goal is simply to generate yaw moment to stabilize the vehicle body and control the current yaw rate of the vehicle to approach the target yaw rate, that is, to control the current yaw rate of the vehicle to change towards the target yaw rate.

[0141] In some embodiments, to ensure the vehicle can steer, it can be confirmed in advance whether the vehicle meets the rotation conditions. If the rotation conditions are met, the vehicle is rotated. For example, the rotation conditions include: the torque generated by the vehicle's drive wheels meets the rotation conditions, and the first front wheel does not produce displacement. Here, the torque generated by the drive wheels meets the condition to ensure that the torque generated by the drive wheels can cause the vehicle to rotate. The first front wheel does not produce displacement to ensure that the first front wheel (i.e., the front wheel that needs to be stationary) does not move as the center of rotation during the rotation process. It can be seen that by checking the rotation conditions, the feasibility of rotation can be improved, and the safety of the vehicle can be enhanced. The condition checking process is described below with reference to step S103.

[0142] In some embodiments, after step S101 and before step S102, the turning method shown in FIG1 may further include step S103.

[0143] Step S103: Determine whether the vehicle meets at least one of the following conditions: the vehicle rotation condition or the first front wheel non-slip condition, based at least on the vertical load of the first rear wheel, the vertical load of the second rear wheel, the slip ratio of the first rear wheel, and the slip ratio of the second rear wheel.

[0144] In some embodiments, the steering control device needs to determine that the vehicle meets the rotation conditions before driving the first and second rear wheels of the vehicle to turn.

[0145] In other embodiments, the steering control device needs to determine that the first front wheel meets the non-slip condition before the first and second rear wheels of the vehicle are turned.

[0146] In some other embodiments, before the first and second rear wheels of the vehicle are turned, the steering control device needs to determine that the vehicle meets the rotation condition and the first front wheel meets the non-slip condition.

[0147] In some embodiments, the steering control device determines whether the vehicle meets at least one of the following conditions: the vertical load of the first rear wheel, the vertical load of the second rear wheel, the slip ratio of the first rear wheel, and the slip ratio of the second rear wheel.

[0148] Here, the vertical loads on the first and second rear wheels can be obtained directly by load sensors or indirectly by estimation. The slip ratios of the first and second rear wheels can be calculated using relevant parameters. In some embodiments, the slip ratio of the first rear wheel is related to the angular velocity of the first rear wheel, the effective rolling radius of the first rear wheel, the angular velocity of the vehicle rotating around the first front wheel, and the distance between the first rear wheel and the first front wheel. The slip ratio of the second rear wheel is related to the angular velocity of the second rear wheel, the effective rolling radius of the second rear wheel, the angular velocity of the vehicle rotating around the first front wheel, and the distance between the second rear wheel and the first front wheel.

[0149] For example, the slip ratio of the first rear wheel satisfies the following formula (3):

[0150] Where s1 is the slip ratio of the first rear wheel, w r1 R is the angular velocity of the first rear wheel, r1 is the effective rolling radius of the first rear wheel, w is the angular velocity of the vehicle rotating around the first front wheel, and R1 is the distance between the first rear wheel and the first front wheel.

[0151] The slip ratio of the second rear wheel satisfies the following formula (4):

[0152] Where s2 is the slip ratio of the first rear wheel, w r2 R1 is the angular velocity of the second rear wheel, r2 is the effective rolling radius of the second rear wheel, w is the angular velocity of the vehicle rotating around the first front wheel, and R1 is the distance between the second rear wheel and the first front wheel.

[0153] In some embodiments, if the vehicle simultaneously meets the vehicle rotation condition and the first front wheel non-slip condition, the steering control device performs step S102 as described above. In some embodiments, if the vehicle does not meet either the vehicle rotation condition or the first front wheel non-slip condition, the steering control device controls the vehicle's brake fluid pressure and motor torque to be slowly unloaded to 0, and displays "Steering function cannot be entered" on the vehicle display screen (e.g., the instrument cluster).

[0154] In some embodiments, the rotation conditions are related to at least one of the following: the maximum output torque of the motor corresponding to the first rear wheel, the maximum output torque of the motor corresponding to the second rear wheel, the reduction ratio of the reducers of the motors corresponding to the first and second rear wheels, the effective rolling radius of the first and second rear wheels, the maximum longitudinal force coefficient between the first rear wheel and the current road surface, the maximum longitudinal force coefficient between the second rear wheel and the current road surface, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the driving force of the second front wheel, the lateral force coefficient of the first rear wheel, the longitudinal force coefficient of the second rear wheel, the lateral force coefficient of the second rear wheel, the driving force of the second front wheel, the track width between the first and second rear wheels, the wheelbase of the vehicle, the rotational resistance of the first front wheel, the moment of inertia of the vehicle, or the angular acceleration of the vehicle. Here, the maximum longitudinal force coefficient between the first and second rear wheels and the current road surface is related to the ground adhesion coefficient of the current road surface. Here, lateral refers to the left-right horizontal direction of the vehicle, which is perpendicular to the direction of motion or travel.

[0155] The non-slip condition is related to the maximum lateral static friction of the first front wheel, the maximum longitudinal static friction of the first front wheel, the longitudinal force coefficient of the first rear wheel, the lateral force coefficient of the second rear wheel, the longitudinal force coefficient of the second rear wheel, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the reaction force of the driving force of the second front wheel, and the vehicle's axle design coefficient. The vehicle's axle design coefficient is related to at least one of the track width between the first and second rear wheels or the vehicle's wheelbase. Thus, by using multiple parameters to determine whether the vehicle meets the rotation condition and whether the first front wheel meets the non-slip condition, the accuracy and safety of the steering process can be improved.

[0156] Here, the longitudinal force coefficient and lateral force coefficient of the first rear wheel are related to the slip ratio of the first rear wheel, and the longitudinal force coefficient and lateral force coefficient of the second rear wheel are related to the slip ratio of the second rear wheel. The longitudinal force coefficient of the wheel is expressed as the ratio of the longitudinal force to the vertical load on the wheel, and the lateral force coefficient is the ratio of the lateral force to the vertical load on the wheel when the vehicle's slip angle is 16°. It should be noted that, as can be seen from the wheel's attachment ellipse, under the same slip ratio, the lateral force coefficient of the wheel no longer increases when the vehicle's slip angle increases to 16°. Therefore, the lateral force coefficient at a slip angle of 16° is taken as the basis for calculating the lateral force on the wheel.

[0157] In some embodiments, the steering control device may obtain the longitudinal force coefficient of the first rear wheel at the current slip ratio according to FIG9. and lateral force coefficient For example, as shown in Figure 9, the maximum longitudinal force coefficient of the first rear wheel on a dry asphalt road surface. Greater than the maximum longitudinal force coefficient of the first rear wheel on a dry cement road surface

[0158] In some embodiments, the left front wheel is the front wheel that needs to be stationary (i.e., the left front wheel is the first front wheel), and the vehicle rotates in a counterclockwise direction. The aforementioned vehicle rotation conditions and the non-slip conditions of the first front wheel are described.

[0159] In some embodiments, as shown in Figure 10, the left front wheel is the front wheel that needs to be stationary (i.e., the first front wheel is the left front wheel), and the vehicle rotates counterclockwise. That is, during the turning process, the vehicle will rotate counterclockwise around the left front wheel as the center of rotation. The driving force generated forward by the vehicle's second front wheel (i.e., the right front wheel) is F. FR The driving force generated by the vehicle's first rear wheel (i.e., the left rear wheel) is F. RL The driving force generated forward by the vehicle's second rear wheel (i.e., the right rear wheel) is F. RR The steering control device determines whether the vehicle can steer at this time; that is, the steering control device determines whether the vehicle meets the rotation conditions and whether the first front wheel meets the non-slip condition.

[0160] The rotation conditions of the vehicle satisfy the following formulas (5), (6), and (7): F RL ≥f lrl_max (5) F RR ≥f lrr_max (6)

[0161] Among them, F RL For the driving force of the first rear wheel (i.e., the left rear wheel), F RR For the driving force of the second rear wheel (i.e., the right rear wheel), F FR For the driving force of the second front wheel (i.e., the right front wheel), f lrm_max f is the maximum longitudinal static friction force of the first rear wheel (i.e., the left rear wheel). lrr_max Where B is the maximum longitudinal static friction force of the second rear wheel (i.e., the right rear wheel), B is the vehicle's track width, L is the vehicle's wheelbase, and f is the maximum longitudinal static friction force of the second rear wheel (i.e., the right rear wheel). srl f is the lateral frictional resistance of the first rear wheel (i.e., the left rear wheel). srr f is the lateral frictional resistance of the second rear wheel (i.e., the right rear wheel). FL J is the rotational resistance of the first front wheel (i.e., the left front wheel). C Let the moment of inertia of the entire vehicle be _____. Let be the angular acceleration of the vehicle.

[0162] The non-slip condition of the first front wheel satisfies the following formulas (8) and (9): f sideway ≥F′ crrcosδ (8) flongitudinal≥|F′ RL -F′ crr sinδ-F′ FR | (9)

[0163] Among them, f sideway F' is the maximum lateral static friction force of the first front wheel (i.e., the left front wheel), and f' is the maximum longitudinal static friction force of the first front wheel (i.e., the left front wheel). RL The driving force F for the first rear wheel (i.e., the left rear wheel) RL The reaction force, F′ crr The component of the driving force F of the second rear wheel (i.e., the right rear wheel) crr The reaction force, F′ FR The driving force F for the second front wheel FR The reaction force, δ, is the axle design coefficient of the vehicle, where δ = arctan(B / L), F trr This is the component of the driving force for the second rear wheel (i.e., the right rear wheel).

[0164] In some embodiments, after vehicle slippage occurs, the steering control device can look up the longitudinal force coefficient and lateral force coefficient of the current wheel in a table, and then obtain the longitudinal friction resistance and lateral friction resistance of the current wheel. For example, the steering control device can obtain the longitudinal force coefficient and lateral force coefficient of the first rear wheel and the second rear wheel at the current slip rate using Figure 9.

[0165] For example, the lateral friction resistance of the first rear wheel satisfies the following formula (10), the longitudinal friction resistance of the first rear wheel satisfies the following formula (11), the lateral friction resistance of the second rear wheel satisfies the following formula (12), and the longitudinal friction resistance of the second rear wheel satisfies the following formula (13):

[0166] in, This represents the lateral force coefficient of the first rear wheel under the current slip ratio. This represents the longitudinal force coefficient of the first rear wheel under the current slip ratio. This represents the lateral force coefficient of the second rear wheel under the current slip ratio. F is the longitudinal force coefficient of the second rear wheel under the current slip ratio. zrl For the vertical load on the first rear wheel, F zrr This is the vertical load on the second rear wheel.

[0167] In some embodiments, the longitudinal frictional resistance of the first rear wheel can be considered to be related to the driving force F of the first rear wheel. RLSince they are of equal magnitude, the longitudinal frictional resistance of the second rear wheel can be considered to be equal to the driving force F of the second rear wheel. RR They are the same size.

[0168] Substituting equations (10) to (13) into the vehicle's rotation condition yields equations (14) to (16):

[0169] Among them, T RL_max T represents the maximum torque of the motor corresponding to the first rear wheel. RR_max Let be the maximum torque of the motor corresponding to the second rear wheel, and let i be the reduction ratio of the reducer for the motors corresponding to the first and second rear wheels. This is the maximum longitudinal force coefficient between the first rear wheel and the current road surface. This is the maximum longitudinal force coefficient between the second rear wheel and the current road surface.

[0170] Substituting equations (10) to (13) into the non-slip condition of the first front wheel, we can obtain the following equations (17) and (18):

[0171] From the above formulas (14) to (18), it can be seen that the steering control device can obtain the maximum longitudinal force coefficient between the first rear wheel and the current road surface (i.e., ...) through Figure 9. The steering control device can obtain the maximum longitudinal force coefficient between the second rear wheel and the current road surface (i.e., ...) from Figure 9. Based on the slip ratio (s1) of the first rear wheel, the longitudinal force coefficient (i.e., s1) of the first rear wheel under the current slip ratio is obtained through Figure 9. ) and the lateral force coefficient of the first rear wheel at the current slip ratio (i.e. Based on the slip ratio (s2) of the second rear wheel, the longitudinal force coefficient (i.e., s2) of the second rear wheel under the current slip ratio is obtained through Figure 9. ) and the lateral force coefficient of the second rear wheel under the current slip ratio (i.e. ).

[0172] In some embodiments, the steering control device determines whether the vehicle meets the vehicle rotation condition and the first front wheel non-slip condition according to the above formulas (14) to (18).

[0173] In some embodiments, as shown in Figure 11, steering around the center of the vehicle is achieved by a four-wheel drive vehicle. However, this method requires a large lateral space. When the vehicle is parked in the narrow parking space shown in Figure 11, the steering method of the four-wheel drive vehicle will not be able to complete the entry and exit of the parking space due to insufficient lateral space.

[0174] In some embodiments, as shown in Figure 12, the vehicle includes a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel. Using methods from some embodiments of this disclosure, the left front wheel is locked in place by coordinating the vehicle's braking system, or by controlling the left front wheel to remain stationary using the output torque of the motor corresponding to the left front wheel. The left rear wheel is driven by the output torque of the left rear wheel, and the right rear wheel is driven by the output torque of the right rear wheel, allowing the vehicle to rotate around the left front wheel to achieve steering. When the distance between the left front wheel and the rear obstacle is greater than the furthest distance between the vehicle body and the left front wheel, the vehicle can successfully complete parallel parking in a narrow parking space. Compared to the steering method shown in Figure 1, the method from some embodiments of this disclosure requires less lateral space, improving the vehicle's flexibility and maneuverability, and better handling narrow parking environments.

[0175] In the embodiment shown in Figure 1, the steering control device can control the first front wheel to be stationary relative to the vehicle and drive the first rear wheel and the second rear wheel to rotate. It also controls the first rear wheel and the second rear wheel to drive in opposite directions so that the vehicle can turn around the first front wheel. This allows the vehicle to turn around the first front wheel without changing the vehicle's steering system and drive mode, which can improve the vehicle's steering ability, flexibility and passability, and better cope with narrow parking environments. For example, it can enable side parking in narrow parking spaces.

[0176] The following describes the system architecture used in some embodiments of this disclosure. It should be noted that the system architecture and business scenarios described in this disclosure are for the purpose of more clearly illustrating the technical solutions of this disclosure and do not constitute a limitation on the technical solutions provided by this disclosure. Those skilled in the art will understand that, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions provided by this disclosure are equally applicable to similar technical problems.

[0177] As shown in Figure 13, the vehicle 130 includes a steering control device 1305 and multiple wheels. These multiple wheels can be distributed on both sides along the vehicle's direction of travel; that is, the multiple wheels include left and right wheels. For example, the multiple wheels include a left front wheel 1301, a right front wheel 1302, a left rear wheel 1303, and a right rear wheel 1304, etc.

[0178] Vehicle 130 is a vehicle with independent rear wheel drive capability provided in some embodiments of this disclosure. Vehicle 130 can be a distributed three-motor vehicle, a four-wheel independent drive vehicle, or a rear-wheel independent drive vehicle, etc.

[0179] The steering control device 1305 is a module with data processing and control capabilities, used to process relevant data of the vehicle 130 and control the vehicle 130 to perform relevant functions. For example, the steering control device 1305 can implement the steering method in the embodiment of FIG1. ​​For example, the steering control device 1305 can keep the left front wheel 1301 stationary, determine the output torque of the left rear wheel 1303 based on the state information of the left rear wheel 1303, determine the output torque of the right rear wheel 1304 based on the state information of the right rear wheel 1304, drive the left rear wheel 1303 based on the output torque of the left rear wheel 1303, and drive the right rear wheel 1304 based on the output torque of the right rear wheel 1304, so that the vehicle 130 can steer around the stationary front wheel (i.e., the left front wheel 1301).

[0180] In some embodiments, the steering control device 1305 may be a physical device. For example, the steering control device 1305 may include one or more of the following modules: a central processing unit (CPU), a microprocessor unit (MPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), a coprocessor (assisting the CPU in completing corresponding processing and applications), a microcontroller unit (MCU), or an electronic control unit (ECU), etc. Of course, the above description assumes the steering control device 1305 is an in-vehicle device. In some embodiments, the steering control device 1305 may be a physical device located outside the vehicle, such as a server, cloud, or host computer. In some embodiments, the steering control device 1305 may be a software module, such as a virtual machine, software, program code, or a container.

[0181] As mentioned in the foregoing embodiments, the steering control device 1305 can be located outside the vehicle. It should be understood that when the steering control device 1305 is located outside the vehicle 130, the vehicle 130 and the steering control device 1305 can communicate with each other. For example, they can be directly connected via wired communication, such as through tangible media like metal wires or optical fibers. Alternatively, they can be indirectly connected via wireless communication, such as through ultra-wideband (UWB) technology, long-term evolution (LTE) technology, 5th generation mobile networks or 5th generation wireless systems, 5th-Generation (5G), Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), or Universal Mobile Telecommunications System (UMTS).

[0182] In some embodiments, the foregoing is provided to facilitate understanding of an exemplary vehicle provided in this disclosure and is not intended to limit the application scenarios of this disclosure. The solutions provided in this disclosure are also applicable to similar devices that use wheeled devices for travel and have data processing capabilities, such as logistics robots. Furthermore, the number of wheels of the vehicle 130 shown in Figure 13 is also an example; in actual operation, the vehicle 130 may contain more (e.g., six wheels, eight wheels) or fewer (e.g., three wheels) wheels.

[0183] As shown in Figure 14, the vehicle 140 includes a steering mechanism 1405, a braking control system 1406, a vehicle controller 1407, a yaw rate sensor 1408, a first wheel speed sensor 1409, a second wheel speed sensor 1410, a first reducer 1411, a first motor 1412, a second motor 1413, a second reducer 1414, and multiple wheels. The multiple wheels can be distributed on both sides along the vehicle's direction of travel; that is, the multiple wheels include left and right wheels. For example, the multiple wheels include a left front wheel 1401, a right front wheel 1402, a left rear wheel 1403, and a right rear wheel 1404. The vehicle 140 can drive the left rear wheel 1403 via the first motor 1412 and the right rear wheel 1404 via the second motor 1413.

[0184] Here, the steering mechanism 1405 is used to control the driving direction of the vehicle. For example, the steering mechanism 1405 can control the steering of the left front wheel 1401 and the right front wheel 1402 of the vehicle, thereby controlling the driving direction of the vehicle.

[0185] Braking control 1406 is used to brake the left front wheel 1401 and the right front wheel 1402. For example, braking control 1406 brakes and locks the left front wheel 1401 to keep the left front wheel 1401 stationary.

[0186] The vehicle controller 1407 is configured to acquire signals, control the vehicle, and forward relevant information from various devices. For example, the vehicle controller 1407 acquires wheel speed information collected by the first wheel speed sensor 1409 and the second wheel speed sensor 1410. As another example, the vehicle controller 1407 sends steering commands to the steering mechanism 1405 to control the vehicle's direction of travel. Yet another example, the vehicle controller 1407 sends commands to the braking control 1406 to brake the left front wheel 1401 and the right front wheel 1402.

[0187] The yaw rate sensor 1408 is configured to collect yaw information of the vehicle, such as the lateral acceleration or yaw rate of the vehicle, and send the collected yaw information to the vehicle controller 1407.

[0188] The first wheel speed sensor 1409 is configured to collect wheel speed information of the left rear wheel 1403 and send the collected wheel speed information of the left rear wheel 1403 to the vehicle controller 1407.

[0189] The second wheel speed sensor 1410 is configured to collect wheel speed information of the right rear wheel 1404 and send the collected wheel speed information of the right rear wheel 1404 to the vehicle controller 1407. In some embodiments, the vehicle speed is calculated using the wheel speed information of the left rear wheel 1403 and the wheel speed information of the right rear wheel 1404.

[0190] The first reducer 1411 is configured to change the rotational speed; for example, the first reducer 1411 is configured to adjust the wheel speed of the left rear wheel 1403.

[0191] The first motor 1412 is configured to drive the left rear wheel 1403.

[0192] The second motor 1413 is configured to drive the right rear wheel 1404.

[0193] The second reducer 1414 is configured to change the rotational speed; for example, the second reducer 1414 is configured to adjust the wheel speed of the right rear wheel 1404. In some embodiments, the reduction ratios of the first reducer 1411 and the second reducer 1414 may be the same.

[0194] The various devices can communicate with each other via the Controller Area Network (CAN) network.

[0195] In some embodiments, some embodiments of this disclosure can implement the steering method of FIG1 above. For example, this disclosure can control the left front wheel 1401 or the right front wheel 1402 to be stationary relative to the vehicle body by braking and locking the left front wheel 1401 or the right front wheel 1402 through braking control 1406 (for example, controlling the left front wheel 1401 to be stationary relative to the vehicle body by braking and locking the left front wheel 1401). The output torque of the left rear wheel 1403 is determined according to the state information of the left rear wheel 1403, and the output torque of the right rear wheel 1404 is determined according to the state information of the right rear wheel 1404. Based on the output torque of the left rear wheel 1403, the left rear wheel 1403 is driven by the first motor 1412, and based on the output torque of the right rear wheel 1404, the right rear wheel 1404 is driven by the second motor 1413. The driving directions of the left rear wheel 1403 and the right rear wheel 1404 are controlled to be opposite, so that the vehicle 140 can be steered around the stationary front wheel (i.e., the left front wheel 1401). In this way, vehicle steering can be achieved without changing the vehicle's steering system and drive method, which can improve the vehicle's steering ability, agility, and passability.

[0196] As shown in Figure 15, the vehicle 150, based on the vehicle 140, may further include a differential 1415, a third reducer 1416, a third motor 1417, a third wheel speed sensor 1418, and a fourth wheel speed sensor 1419. The vehicle 150 can drive the left front wheel 1401 and right front wheel 1402 via the third motor 1417, drive the left rear wheel 1403 via the first motor 1412, and drive the right rear wheel 1404 via the second motor 1413.

[0197] The differential 1415 enables the left front wheel 1401 and the right front wheel 1402 to rotate at different speeds.

[0198] The third reducer 1416 is configured to change the rotational speed; for example, the third reducer 1416 is configured to adjust the wheel speed of the left front wheel 1401 and the right front wheel 1402.

[0199] The third motor 1417 is configured to drive the left front wheel 1401 and the right front wheel 1402. For example, the torque of the third motor 1417 controls the left front wheel 1401 to remain stationary relative to the vehicle body.

[0200] The third wheel speed sensor 1418 is configured to collect wheel speed information of the left front wheel 1401 and send the collected wheel speed information of the left front wheel 1401 to the vehicle controller 1407.

[0201] The fourth wheel speed sensor 1419 is configured to collect wheel speed information of the right front wheel 1402 and send the collected wheel speed information of the right front wheel 1402 to the vehicle controller 1407. In some embodiments, the vehicle speed is calculated using the wheel speed information of the left rear wheel 1403 and the wheel speed information of the right rear wheel 1404.

[0202] In some embodiments, the present disclosure can implement the steering method of FIG1 above. For example, the present disclosure can control the left front wheel 1401 or the right front wheel 1402 to be stationary by braking and locking the left front wheel 1401 or the right front wheel 1402 by braking and locking the left front wheel 1401 (e.g., braking and locking the left front wheel 1401 to control the left front wheel 1401 to be stationary) or control the left front wheel 1401 to be stationary by the torque of the third motor 1417. The output torque of the left rear wheel 1403 is determined according to the state information of the left rear wheel 1403, and the output torque of the right rear wheel 1404 is determined according to the state information of the right rear wheel 1404. Based on the output torque of the left rear wheel 1403, the left rear wheel 1403 is driven by the first motor 1412, and based on the output torque of the right rear wheel 1404, the right rear wheel 1404 is driven by the second motor 1413. The driving directions of the left rear wheel 1403 and the right rear wheel 1404 are controlled to be opposite, so that the vehicle 150 can be steered around the stationary front wheel (i.e., the left front wheel 1401). In this way, vehicle steering can be achieved without changing the vehicle's steering system and drive method, which can improve the vehicle's steering ability, agility, and passability.

[0203] Some embodiments of this disclosure can also determine the output torque of the right front wheel 1402, and drive the right front wheel 1402 through the third motor 1417 based on the output torque of the right front wheel 1402, thereby controlling the stability of the yaw rate of the vehicle 150, making the vehicle 150 more stable and controllable during the turning process.

[0204] As shown in Figure 16, the vehicle 160, based on the vehicle 140, may further include a fourth reducer 1420, a fourth motor 1421, a fifth motor 1422, a fifth reducer 1423, a third wheel speed sensor 1418, and a fourth wheel speed sensor 1419. The vehicle 160 can drive the left front wheel 1401 via the fourth motor 1421, the right front wheel 1402 via the fifth motor 1422, the left rear wheel 1403 via the first motor 1412, and the right rear wheel 1404 via the second motor 1413.

[0205] The fourth motor 1421 is configured to convert chemical energy into kinetic energy for the vehicle, thereby driving the left front wheel 1401 to rotate. For example, the torque of the fourth motor 1421 can be used to keep the left front wheel 1401 stationary.

[0206] The fourth reducer 1420 is configured to change the rotational speed; for example, the fourth reducer 1420 is configured to adjust the wheel speed of the left front wheel 1401.

[0207] The fifth motor 1422 is configured to convert chemical energy into the vehicle's kinetic energy, thereby driving the right front wheel 1402 to rotate.

[0208] The fifth reducer 1423 is configured to change the rotational speed; for example, the fifth reducer 1423 is configured to adjust the wheel speed of the right front wheel 1402. In some embodiments, the reduction ratios of the fourth reducer 1420 and the fifth reducer 1423 may be the same.

[0209] The third wheel speed sensor 1418 is configured to collect wheel speed information of the left front wheel 1401 and send the collected wheel speed information of the left front wheel 1401 to the vehicle controller 1407.

[0210] The fourth wheel speed sensor 1419 is configured to collect wheel speed information of the right front wheel 1402 and send the collected wheel speed information of the right front wheel 1402 to the vehicle controller 1407.

[0211] In some embodiments, some embodiments of this disclosure can implement the steering method of FIG1 above. For example, this disclosure can control the left front wheel 1401 or the right front wheel 1402 to be stationary by braking and locking the left front wheel 1401 or the right front wheel 1402 through braking control 1406 (e.g., braking and locking the left front wheel 1401 to control the left front wheel 1401 to be stationary) or control the left front wheel 1401 to be stationary through the torque of the fourth motor 1421. The output torque of the left rear wheel 1403 is determined according to the state information of the left rear wheel 1403, and the output torque of the right rear wheel 1404 is determined according to the state information of the right rear wheel 1404. Based on the output torque of the left rear wheel 1403, the left rear wheel 1403 is driven through the first motor 1412, and based on the output torque of the right rear wheel 1404, the right rear wheel 1404 is driven through the second motor 1413. The driving directions of the left rear wheel 1403 and the right rear wheel 1404 are controlled to be opposite, so that the vehicle 160 can be steered around the stationary front wheel (i.e., the left front wheel 1401). In this way, vehicle steering can be achieved without changing the vehicle's steering system and drive method, which can improve the vehicle's steering ability, agility, and passability.

[0212] Furthermore, some embodiments of this disclosure can also determine the output torque of the right front wheel 1402, and drive the right front wheel 1402 through the fifth motor 1422 based on the output torque of the right front wheel 1402, thereby controlling the stability of the yaw rate of the vehicle 160, making the vehicle 160 more stable and controllable during the steering process.

[0213] The methods of some embodiments of this disclosure have been described in detail above. The apparatus of some embodiments of this disclosure is provided below.

[0214] As shown in Figure 17, the steering control device 170 is included in a vehicle, which includes a first front wheel, a first rear wheel, and a second rear wheel. The steering control device 170 may include a processing unit 1701 and a drive unit 1702. The steering control device 170 is configured to implement the aforementioned steering method, such as the steering method in the embodiment shown in Figure 1.

[0215] It should be noted that the above division of multiple units is only a logical division based on function and does not constitute a limitation on the structure of the steering control device 170. In practical applications, some functional modules may be further subdivided into more smaller functional modules, and some functional modules may be combined into a single functional module.

[0216] In some embodiments, the processing unit 1701 is configured to keep the first front wheel of the vehicle stationary relative to the vehicle. The drive unit 1702 is configured to drive the first and second rear wheels of the vehicle to rotate, thereby steer the vehicle about the first front wheel. Here, the first and second rear wheels drive in opposite directions.

[0217] In some embodiments, the processing unit 1701 is further configured to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle, or to control the first front wheel to be stationary relative to the vehicle by torque.

[0218] In some embodiments, the processing unit 1701 is further configured to determine, based on steering input information, the front wheels of the vehicle that need to be stationary. Here, the first front wheel is the front wheel of the vehicle that needs to be stationary.

[0219] In some embodiments, the steering input information is further configured to determine at least one of the following: the direction of rotation of the vehicle or the required turning angle of the vehicle.

[0220] In some embodiments, the driving direction of the first and second rear wheels is related to the vehicle's rotation direction. Here, the vehicle's rotation direction is clockwise and counterclockwise, respectively.

[0221] In some embodiments, the required rotation angle of the front wheels and the vehicle that need to be stationary can be selected through vehicle-mounted selection, button selection, remote control selection, and steering wheel selection. The rotation direction of the vehicle can also be selected through vehicle-mounted selection, button selection, remote control selection, and gear selection.

[0222] In some embodiments, the processing unit 1701 is further configured to determine the output torque of the first rear wheel based on the state information of the first rear wheel, and the driving unit 1702 is further configured to drive the first rear wheel to rotate based on the output torque of the first rear wheel.

[0223] In some embodiments, the processing unit 1701 is further configured to determine the output torque of the second rear wheel based on the state information of the second rear wheel, and the driving unit 1702 is further configured to drive the first rear wheel to rotate based on the output torque of the second rear wheel.

[0224] In some embodiments, the state information of the first rear wheel includes at least one of the wheel speed of the first rear wheel, the wheel acceleration of the first rear wheel, the current slip ratio of the first rear wheel, or the target slip ratio of the first rear wheel, and the state information of the second rear wheel includes at least one of the wheel speed of the second rear wheel, the wheel acceleration of the second rear wheel, the current slip ratio of the second rear wheel, or the target slip ratio of the second rear wheel.

[0225] In some embodiments, the processing unit 1701 is further configured to determine the output torque of the first rear wheel based on the target slip ratio of the first rear wheel, the current slip ratio of the first rear wheel, and the torque control method for the first rear wheel. The output torque of the first rear wheel is configured to cause the slip ratio of the first rear wheel to change toward the target slip ratio of the first rear wheel. In some embodiments, the output torque of the first rear wheel can be determined using a PID control algorithm.

[0226] In some embodiments, the difference between the current slip ratio of the first rear wheel and the target slip ratio of the first rear wheel is used as the input of the segmented PID control, the torque control mode for the first rear wheel is used as the enable flag for the segmented PID control stage jump, and the output torque of the first rear wheel is output.

[0227] In some embodiments, the processing unit 1701 is further configured to determine a torque control method for the first rear wheel based on the wheel speed and wheel acceleration of the first rear wheel.

[0228] In some embodiments, the torque control method for the first rear wheel is configured to indicate the torque adjustment direction and the torque adjustment rate for the first rear wheel, wherein the torque adjustment direction is one of increasing torque, decreasing torque, and maintaining torque, and the torque adjustment rate for the first rear wheel is configured to indicate the force of adjusting the torque of the first rear wheel.

[0229] In some embodiments, the processing unit 1701 is further configured to determine the output torque of the second rear wheel based on the target slip ratio of the second rear wheel, the current slip ratio of the second rear wheel, and the torque control method for the second rear wheel. The output torque of the second rear wheel is configured to cause the slip ratio of the second rear wheel to change toward the target slip ratio of the second rear wheel. In some embodiments, the output torque of the second rear wheel can be determined using a piecewise PID control algorithm.

[0230] In some embodiments, the difference between the current slip ratio of the second rear wheel and the target slip ratio of the second rear wheel is used as the input of the segmented PID control, and the torque control mode for the second rear wheel is used as the enable flag for the segmented PID control stage jump, and the output torque of the second rear wheel is output.

[0231] In some embodiments, the processing unit 1701 is further configured to determine a torque control method for the second rear wheel based on the wheel speed and wheel acceleration of the second rear wheel.

[0232] In some embodiments, the torque control method for the second rear wheel is configured to indicate the torque adjustment direction and the torque adjustment rate for the second rear wheel, wherein the torque adjustment direction is one of increasing torque, decreasing torque, and maintaining torque, and the torque adjustment rate for the second rear wheel is configured to indicate the force of adjusting the torque of the second rear wheel.

[0233] In some embodiments, the drive unit 1702 is also configured to drive the second front wheel of the vehicle to rotate.

[0234] In some embodiments, the processing unit 1701 is further configured to determine the output torque of the second front wheel of the vehicle based on the vehicle's current yaw rate and the vehicle's target yaw rate. The drive unit 1702 is further configured to drive the second front wheel to rotate based on the output torque of the second front wheel. Here, the output torque of the second front wheel is configured to cause the vehicle's yaw rate to change toward the vehicle's target yaw rate. In some embodiments, the output torque of the second front wheel can be determined using a piecewise PID control algorithm.

[0235] In some embodiments, the difference between the vehicle's current yaw rate and the vehicle's target yaw rate is used as the input to a piecewise PID control system to output the output torque of the second front wheel.

[0236] In some embodiments, the processing unit 1701 is further configured to determine that the vehicle meets rotation conditions before the first and second rear wheels of the vehicle are rotated. Here, the rotation conditions are related to at least one of the following: the maximum output torque of the motor corresponding to the first rear wheel, the maximum output torque of the motor corresponding to the second rear wheel, the reduction ratio of the reducers of the motors corresponding to the first and second rear wheels, the effective rolling radius of the first and second rear wheels, the maximum longitudinal force coefficient between the first rear wheel and the current road surface, the maximum longitudinal force coefficient between the second rear wheel and the current road surface, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the driving force of the second front wheel, the lateral force coefficient of the first rear wheel, the longitudinal force coefficient of the second rear wheel, the lateral force coefficient of the second rear wheel, the driving force of the second front wheel, the track width between the first and second rear wheels, the wheelbase of the vehicle, the rotational resistance of the first front wheel, the moment of inertia of the vehicle, or the angular acceleration of the vehicle.

[0237] In some embodiments, the processing unit 1701 is further configured to determine that the first front wheel meets a non-slip condition before the first and second rear wheels of the vehicle rotate. Here, the non-slip condition is related to the maximum lateral static friction of the first front wheel, the maximum longitudinal static friction of the first front wheel, the longitudinal force coefficient of the first rear wheel, the lateral force coefficient of the second rear wheel, the longitudinal force coefficient of the second rear wheel, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the reaction force of the driving force of the second front wheel, and the axle design factor of the vehicle, which is related to at least one of the track width between the first and second rear wheels or the wheelbase of the vehicle.

[0238] In some embodiments, the processing unit 1701 is further configured to disengage the vehicle's steering function when the vehicle meets the vehicle's steering disengagement conditions. Here, the vehicle's steering disengagement conditions include one or more of the following: the vehicle's rotation angle reaches the vehicle's required rotation angle, the vehicle's user depresses the brake pedal, the vehicle's steering wheel angle exceeds a first threshold, the electronic parking brake is activated, the vehicle's gear is changed, or the vehicle's user deactivates the steering function.

[0239] It should be noted that the above modules (processing unit 1701 and driving unit 1702) are used to execute the relevant steps of the above method. For example, processing unit 1701 is configured to execute the relevant contents of steps S101 and S103, and driving unit 1702 is configured to execute the relevant contents of step S102.

[0240] Computing devices are devices with processing capabilities. These devices can be physical devices, such as servers (e.g., rack servers) and hosts, or they can be virtual devices, such as virtual machines and containers.

[0241] As shown in Figure 18, the computing device 180 includes a processor 1801, a memory 1802, and one or more programs, and may include a communication interface 1803. It should be understood that this disclosure does not limit the number of processors and memories in the computing device 180.

[0242] Processor 1801 is a module that performs calculations and may include a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor (MP), a digital signal processor (DSP), a micro controller unit (MCU), or one or more integrated circuits for controlling the execution of programs in the above schemes.

[0243] Memory 1802 provides storage space, in which application data, user data, operating system, and computer programs can be optionally stored. Memory 1802 may include read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0244] The memory 1802 can exist independently and be connected to the processor 1801 via a bus. Alternatively, the memory 1802 can be integrated with the processor 1801.

[0245] The communication interface 1803 can be used to perform at least one of the following: providing information input or output to the at least one processor, or receiving or sending data to an externally transmitted device. The communication interface 1803 can be a wired link interface, such as an Ethernet cable, or a wireless link interface (Wi-Fi, Bluetooth, general wireless transmission, and other wireless communication technologies). In some embodiments, the communication interface 1803 may also include a transmitter (such as a radio frequency transmitter, antenna, etc.) or a receiver coupled to the interface.

[0246] In some embodiments of this disclosure, one or more of the aforementioned programs are stored in the aforementioned memory 1802 in the form of program code and are configured to be executed by the aforementioned processor 1801. The programs include instructions for implementing the steps in the aforementioned steering method. For example, the steering method shown in FIG1 is executed. That is, the memory 1802 stores executable instructions, and the processor 1801 executes these executable instructions to implement the aforementioned steering method, for example, the steering method in the embodiment of FIG1. ​​In other words, the memory 1802 stores instructions for executing the steering method.

[0247] Alternatively, the memory 1802 stores executable instructions, and the processor 1801 executes these executable instructions to implement the functions of one or more of the aforementioned processing units and driving units (or devices), thereby realizing the steering method.

[0248] Some embodiments of this disclosure also provide a control system, which includes a control device and a drive device.

[0249] A control device is configured to keep the first front wheel of the vehicle stationary relative to the vehicle; a drive device is configured to drive the first and second rear wheels of the vehicle to rotate so that the vehicle can be steered about the first front wheel, wherein the first and second rear wheels are driven in opposite directions.

[0250] In some embodiments, the control device includes at least one of a brake or a first motor. If the control device includes a brake, the brake is configured to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle. If the control device includes a first motor, the first motor is configured to control the first front wheel to be stationary relative to the vehicle by torque. If the control device includes both a brake and a first motor, the brake is configured to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle, and the first motor is configured to control the first front wheel to be stationary relative to the vehicle by torque. In some embodiments, the brake is the brake control 1406 shown in FIG. 14. In some embodiments, the first motor is the third motor 1417 shown in FIG. 15. In some embodiments, the first motor is the fourth motor 1421 shown in FIG. 16.

[0251] In some embodiments, the drive unit includes a second motor and a third motor, the second motor being configured to drive the first rear wheel of the vehicle to rotate, and the third motor being configured to drive the second rear wheel of the vehicle to rotate. In some embodiments, the second motor is the first motor 1412 shown in FIG. 14, and the third motor is the second motor 1413 shown in FIG. 14.

[0252] In some embodiments, the first motor is further configured to drive the second front wheel of the vehicle to rotate; alternatively, the drive unit further includes a fourth motor configured to drive the second front wheel of the vehicle to rotate. In some embodiments, the fourth motor is the fifth motor 1422 shown in FIG. 16.

[0253] In some embodiments, the control system further includes a steering controller configured to steer the vehicle about the first front wheel. In some embodiments, the steering controller is the steering mechanism 1405 shown in FIG. 14, or the vehicle controller 1407 shown in FIG. 14.

[0254] In some embodiments, the control device is further configured to determine, based on steering input information, the front wheels of the vehicle that need to be stationary. Here, the first front wheel is the front wheel of the vehicle that needs to be stationary.

[0255] In some embodiments, the steering input information is further configured to determine at least one of the following: the direction of rotation of the vehicle or the required turning angle of the vehicle.

[0256] In some embodiments, the driving direction of the first and second rear wheels is related to the vehicle's rotation direction. Here, the vehicle's rotation direction is clockwise and counterclockwise, respectively.

[0257] In some embodiments, the control device is further configured to determine the output torque of the first rear wheel based on the state information of the first rear wheel, and the drive device is further configured to drive the first rear wheel to rotate based on the output torque of the first rear wheel.

[0258] In some embodiments, the control device is further configured to determine the output torque of the second rear wheel based on the state information of the second rear wheel, and the drive device is further configured to drive the first rear wheel to rotate based on the output torque of the second rear wheel.

[0259] In some embodiments, the state information of the first rear wheel includes at least one of the wheel speed of the first rear wheel, the wheel acceleration of the first rear wheel, the current slip ratio of the first rear wheel, or the target slip ratio of the first rear wheel, and the state information of the second rear wheel includes at least one of the wheel speed of the second rear wheel, the wheel acceleration of the second rear wheel, the current slip ratio of the second rear wheel, or the target slip ratio of the second rear wheel.

[0260] In some embodiments, the control device is further configured to determine the output torque of the first rear wheel based on the target slip ratio of the first rear wheel, the current slip ratio of the first rear wheel, and the torque control mode for the first rear wheel, wherein the output torque of the first rear wheel is configured to cause the slip ratio of the first rear wheel to change toward the target slip ratio of the first rear wheel.

[0261] In some embodiments, the control device is further configured to determine a torque control mode for the first rear wheel based on the wheel speed and wheel acceleration of the first rear wheel.

[0262] In some embodiments, the torque control method for the first rear wheel is configured to indicate the torque adjustment direction and the torque adjustment rate for the first rear wheel, wherein the torque adjustment direction is one of increasing torque, decreasing torque, and maintaining torque, and the torque adjustment rate for the first rear wheel is configured to indicate the force of adjusting the torque of the first rear wheel.

[0263] In some embodiments, the control device is further configured to determine the output torque of the second rear wheel based on the target slip ratio of the second rear wheel, the current slip ratio of the second rear wheel, and the torque control mode for the second rear wheel, wherein the output torque of the second rear wheel is configured to cause the slip ratio of the second rear wheel to change toward the target slip ratio of the second rear wheel.

[0264] In some embodiments, the control device is further configured to determine a torque control mode for the second rear wheel based on the wheel speed and wheel acceleration of the second rear wheel.

[0265] In some embodiments, the torque control method for the second rear wheel is configured to indicate the torque adjustment direction and the torque adjustment rate for the second rear wheel, wherein the torque adjustment direction is one of increasing torque, decreasing torque, and maintaining torque, and the torque adjustment rate for the second rear wheel is configured to indicate the force of adjusting the torque of the second rear wheel.

[0266] In some embodiments, the drive unit is also configured to drive the second front wheel of the vehicle to rotate.

[0267] In some embodiments, the control device is further configured to determine the output torque of the second front wheel of the vehicle based on the vehicle's current yaw rate and the vehicle's target yaw rate. The drive device is further configured to drive the second front wheel to rotate based on the output torque of the second front wheel. Here, the output torque of the second front wheel is configured to cause the vehicle's yaw rate to change toward the vehicle's target yaw rate.

[0268] In some embodiments, the control device is further configured to determine that the vehicle meets rotation conditions before driving the first and second rear wheels of the vehicle to rotate. Here, the rotation conditions are related to at least one of the following: the maximum output torque of the motor corresponding to the first rear wheel, the maximum output torque of the motor corresponding to the second rear wheel, the reduction ratio of the reducers of the motors corresponding to the first and second rear wheels, the effective rolling radius of the first and second rear wheels, the maximum longitudinal force coefficient between the first rear wheel and the current road surface, the maximum longitudinal force coefficient between the second rear wheel and the current road surface, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the driving force of the second front wheel, the lateral force coefficient of the first rear wheel, the longitudinal force coefficient of the second rear wheel, the lateral force coefficient of the second rear wheel, the driving force of the second front wheel, the track width between the first and second rear wheels, the wheelbase of the vehicle, the rotational resistance of the first front wheel, the moment of inertia of the vehicle, or the angular acceleration of the vehicle.

[0269] In some embodiments, the control device is further configured to determine that the first front wheel satisfies a non-slip condition before the first and second rear wheels of the vehicle rotate. Here, the non-slip condition is related to the maximum lateral static friction of the first front wheel, the maximum longitudinal static friction of the first front wheel, the longitudinal force coefficient of the first rear wheel, the lateral force coefficient of the second rear wheel, the longitudinal force coefficient of the second rear wheel, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the reaction force of the driving force of the second front wheel, and the axle design factor of the vehicle, which is related to at least one of the track width between the first and second rear wheels or the wheelbase of the vehicle.

[0270] In some embodiments, the control device is further configured to disengage the vehicle's steering function when the vehicle meets the vehicle's steering disengagement conditions. Here, the vehicle's steering disengagement conditions include one or more of the following: the vehicle's rotation angle reaches the vehicle's required rotation angle, the vehicle's user depresses the brake pedal, the vehicle's steering wheel angle exceeds a first threshold, the electronic parking brake is activated, the vehicle's gear is changed, or the vehicle's user deactivates the steering function.

[0271] The control system is configured to implement the aforementioned steering method, such as the steering method in the embodiment of FIG1.

[0272] Some embodiments of this disclosure also provide a vehicle, which is one of a distributed three-motor vehicle, a four-wheel independent drive vehicle, and a rear-wheel independent drive vehicle. The vehicle includes a first front wheel, a first rear wheel, a second rear wheel, and the aforementioned steering control device 170, control system, or the aforementioned computing device 180. The vehicle is configured to implement the aforementioned steering method, such as the steering method in the embodiment of FIG1.

[0273] Some embodiments of this disclosure also provide a computer program product containing instructions. The computer program product may be a software or program product containing instructions capable of running on a computing device or stored on any usable medium. The computer program instructions are used to implement the aforementioned steering method, such as the steering method in the embodiment of FIG1.

[0274] This disclosure also provides a computer-readable storage medium in some embodiments. The computer-readable storage medium includes instructions for implementing the aforementioned redirection method, such as the redirection method in the embodiment of FIG1.

[0275] Here, the computer-readable storage medium can be any available medium that the steering control device can store, or a data storage device such as a data center that contains one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives), etc.

[0276] In some embodiments of this disclosure, the words "exemplarily" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design described as "exemplarily" or "for example" in this disclosure should not be construed as being more preferred or advantageous than other embodiments or designs. Rather, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts by way of example.

[0277] In some embodiments of this disclosure, "at least one" refers to one or more items, and "more than one" refers to two or more items. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, (a and b), (a and c), (b and c), or (a and b and c), where a, b, and c can be single or multiple. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: only A, only B, and A and B, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0278] Furthermore, unless otherwise stated, in some embodiments of this disclosure, the use of ordinal numbers such as "first" and "second" is for distinguishing multiple objects and is not for limiting the order, sequence, priority, or importance of the multiple objects. For example, "first rear wheel" and "second rear wheel" are used only for ease of description and do not indicate a difference in the deployment order or importance of the first and second rear wheels.

[0279] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0280] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A steering method, comprising: The first front wheel of the vehicle is stationary relative to the vehicle. The first and second rear wheels of the vehicle are driven to rotate so that the vehicle can be steered about the first front wheel; wherein the first and second rear wheels are driven in opposite directions.

2. The method of claim 1, wherein, The control of the first front wheel of the vehicle to be stationary relative to the vehicle includes: Braking locks the first front wheel to bring it to a standstill relative to the vehicle, or torque is used to keep the first front wheel stationary relative to the vehicle.

3. The method according to claim 1 or 2, further comprising: Based on the steering input information, the front wheels of the vehicle that need to be stationary are determined, and the first front wheel is the front wheel of the vehicle that needs to be stationary.

4. The method according to claim 3, wherein, The steering input information is also configured to determine at least one of the following: the direction of rotation of the vehicle or the required rotation angle of the vehicle.

5. The method of any one of claims 1 to 4, wherein, The driving direction of the first rear wheel and the second rear wheel is related to the rotation direction of the vehicle.

6. The method according to any one of claims 1 to 5, wherein, The process of driving the first rear wheel of the vehicle to rotate includes: The output torque of the first rear wheel is determined based on the state information of the first rear wheel; The first rear wheel is driven to rotate based on the output torque of the first rear wheel.

7. The method according to claim 6, wherein, Determining the output torque of the first rear wheel based on the state information of the first rear wheel includes: Based on the target slip ratio of the first rear wheel, the current slip ratio of the first rear wheel, and the torque control method for the first rear wheel, the output torque of the first rear wheel is determined. The output torque of the first rear wheel is configured to cause the slip ratio of the first rear wheel to change toward the target slip ratio of the first rear wheel.

8. The method according to claim 7, further comprising: The torque control method for the first rear wheel is determined based on the wheel speed and wheel acceleration of the first rear wheel.

9. The method according to claim 7 or 8, wherein, The torque control method for the first rear wheel is used to indicate at least one of the torque adjustment direction for the first rear wheel or the torque adjustment rate for the first rear wheel. The torque adjustment direction is one of increasing torque, decreasing torque, or maintaining torque. The torque adjustment rate is used to indicate the force of adjusting the torque of the first rear wheel.

10. The method according to any one of claims 6 to 9, wherein, The state information of the first rear wheel includes at least one of the following: wheel speed of the first rear wheel, wheel acceleration of the first rear wheel, current slip rate of the first rear wheel, or target slip rate of the first rear wheel.

11. The method according to any one of claims 1 to 5, wherein, The method of driving the second rear wheel of the vehicle to rotate includes: The output torque of the second rear wheel is determined based on the state information of the second rear wheel; The second rear wheel is driven to rotate based on the output torque of the second rear wheel.

12. The method according to claim 11, wherein, The step of determining the output torque of the second rear wheel based on the state information of the second rear wheel includes: Based on the target slip ratio of the second rear wheel, the current slip ratio of the second rear wheel, and the torque control method for the second rear wheel, the output torque of the second rear wheel is determined. The output torque of the second rear wheel is used to make the slip ratio of the second rear wheel change toward the target slip ratio of the second rear wheel.

13. The method of claim 12, further comprising: The torque control method for the second rear wheel is determined based on the wheel speed and wheel acceleration of the second rear wheel.

14. The method according to claim 12 or 13, wherein, The torque control method for the second rear wheel is used to indicate at least one of the torque adjustment direction for the second rear wheel or the torque adjustment rate for the second rear wheel; The torque adjustment direction is one of increasing torque, decreasing torque, or maintaining torque; The torque adjustment rate is used to indicate the force required to adjust the torque of the second rear wheel.

15. The method according to any one of claims 10 to 14, wherein, The state information of the second rear wheel includes at least one of the following: the wheel speed of the second rear wheel, the wheel acceleration of the second rear wheel, the current slip ratio of the second rear wheel, or the target slip ratio of the second rear wheel.

16. The method according to any one of claims 1 to 15, further comprising: Drive the second front wheel of the vehicle to rotate.

17. The method according to claim 16, wherein, The method of driving the second front wheel of the vehicle to rotate includes: The output torque of the second front wheel is determined based on the vehicle's current yaw rate and the vehicle's target yaw rate. The second front wheel is driven to rotate based on the output torque of the second front wheel, and the output torque of the second front wheel is used to cause the yaw rate of the vehicle to change toward the target yaw rate of the vehicle.

18. The method according to any one of claims 1 to 17, wherein, Before driving the first and second rear wheels of the vehicle to rotate, the method further includes: The vehicle is determined to meet the rotation condition; The rotation conditions are related to at least one of the following: the maximum output torque of the motor corresponding to the first rear wheel, the maximum output torque of the motor corresponding to the second rear wheel, the reduction ratio of the reducers of the motors corresponding to the first and second rear wheels, the effective rolling radius of the first and second rear wheels, the maximum longitudinal force coefficient between the first rear wheel and the current road surface, the maximum longitudinal force coefficient between the second rear wheel and the current road surface, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the driving force of the second front wheel, the lateral force coefficient of the first rear wheel, the longitudinal force coefficient of the second rear wheel, the lateral force coefficient of the second rear wheel, the wheelbase between the first and second rear wheels, the wheelbase of the vehicle, the rotational resistance of the first front wheel, the moment of inertia of the vehicle, or the angular acceleration of the vehicle.

19. The method according to claim 1, wherein, Before driving the first and second rear wheels of the vehicle to rotate, the method further includes: It is determined that the first front wheel meets the non-slip condition; The non-slip condition is related to the maximum lateral static friction of the first front wheel, the maximum longitudinal static friction of the first front wheel, the longitudinal force coefficient of the first rear wheel, the lateral force coefficient of the second rear wheel, the longitudinal force coefficient of the second rear wheel, the vertical load of the first rear wheel, the vertical load of the second rear wheel, the reaction force of the driving force of the second front wheel, and the axle design coefficient of the vehicle. The axle design coefficient of the vehicle is related to at least one of the track width or the wheelbase of the vehicle, wherein the track width is the distance between the first rear wheel and the second rear wheel.

20. The method according to any one of claims 1 to 19, further comprising: If the vehicle meets the conditions for steering disengagement, the vehicle's steering function is disengaged.

21. The method according to claim 20, wherein, The conditions for the vehicle to disengage from steering include one or more of the following: the vehicle's rotation angle reaches the required rotation angle, the user of the vehicle depresses the brake pedal, the vehicle's steering wheel angle exceeds a first threshold, the electronic parking brake is activated, the vehicle's gear is changed, or the user of the vehicle disables the steering function.

22. A steering control device, comprising: The processing unit is configured to keep the first front wheel of the vehicle stationary relative to the vehicle; as well as, The drive unit is configured to drive the first and second rear wheels of the vehicle to rotate so that the vehicle can be steered about the first front wheel, wherein the first and second rear wheels are driven in opposite directions.

23. A control system, comprising: The control device is configured to keep the first front wheel of the vehicle stationary relative to the vehicle; as well as, A drive unit is configured to drive the first and second rear wheels of the vehicle to rotate such that the vehicle is steered about the first front wheel, wherein the first and second rear wheels are driven in opposite directions.

24. The control system according to claim 23, wherein, The control device includes at least one of a brake or a first motor. In the case where the control device includes the brake, the brake is configured to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle; In the case where the control device includes the first motor, the first motor is configured to control the first front wheel to remain stationary relative to the vehicle by means of torque; In the case where the control device includes the brake and the first motor, the brake is configured to brake and lock the first front wheel so that the first front wheel is stationary relative to the vehicle, and the first motor is configured to control the first front wheel to be stationary relative to the vehicle by means of torque.

25. The control system according to claim 23 or 24, wherein, The drive unit includes a second motor and a third motor, the second motor being configured to drive the first rear wheel of the vehicle to rotate; the third motor being configured to drive the second rear wheel of the vehicle to rotate.

26. The control system according to claim 24, wherein, The first motor is also configured to drive the second front wheel of the vehicle to rotate, or the drive unit further includes a fourth motor configured to drive the second front wheel of the vehicle to rotate.

27. The control system according to any one of claims 23 to 26, further comprising a steering controller configured to control the vehicle to steer about the first front wheel.

28. The control system according to any one of claims 23 to 27, for implementing the method according to any one of claims 1 to 21.

29. A computing device comprising a processor and a memory, the memory storing a program, the processor executing the program stored in the memory to cause the computing device to perform the method according to any one of claims 1 to 21.

30. A vehicle comprising a first front wheel, a first rear wheel, a second rear wheel, and a steering control device according to claim 22, a control system according to any one of claims 23 to 28, or a computing device according to claim 29.

31. A computer-readable storage medium, wherein, The computer-readable storage medium is used to store a computer program, the computer program including instructions for performing the method according to any one of claims 1 to 21.

Images